I have taken inspiration from ALL THE BEST XIN players and am combining those PRETTY DIFFERENT PLAYSTYLES to make you adapt to any Matchup/Game thrown at you.

My Main Inspirations are:

1vsAll (Korean Youtuber/Streamer) (Credited for the Aggro Build/Setup)
NA OTP SenKiya#NA1 (Credited for the Safer Build/Setup for harder Matchups)

2 Main Setups
1. Aggro Setup for winning Matchups (Easier Lanes like Yone, Jayce, Rumble, Smolder, Kayle)
2. Safe Setup for losing/hard lanes (vs Statcheckers like Camille, Sett)

When to pick XinZhao Toplane:
Overall Xin likes 4 types of enemies
(Look for these types of champs in the enemy team Im not rating the lane here):
1. Many Ranged Champs (Gives his ult immunity and low cd dashes value)
2. Killable/Oneshottable non Statchecking Melees (So champs like Rengar, Yone, Yas, Akali, Sylas, Riven and NOT many champs like Darius, Garen, Volibear, Nasus, Sett)
3. Low CC Tanks or low Peel (Sion, Ornn are good, not many Leona, Alistars, Jannas)
4. AP Champs as he really likes doing Maw Rush (Insane if they have 2 AP Top JNGL)

When not to pick Xin Toplane:
1. You have 0 Engage/Followup team, who only want to poke/run away/get run into
2. High Disengage/Counter-Engage Champs (Janna, Thresh, Poppy, Gragas, etc.)

Aggro Setup (This is for all lanes where you dont lose the earlygame/lane)
Many Ranged Champs fall into this Category and you wanna build to fight them from lv1.
You go DBlade + Full Earlygame Runes with mostly Conquerer sometimes Lethal Tempo for certain Matchups (Like Fiora)

In lane you can contest most Ranged Champs with an E All-In at lv1 and from lv3 with your combo E->AA->Q->W (VERY FAST BURST COMBO), then either back off or follow up for kill

For Aggro Build usually the first choice is between Eclipse and Stridebreaker (Eclipse is default, Stridebreaker is Tankier, scales better vs many Ranged Champs but is a worse 1 Item 1v1 dueling Spike)

If you want a 1 Size fits all solution I recommend Eclipse -> Titanic -> DD, which will be AT LEAST decent every game if not optimal for most

In General Xin has a very very flexible build you can build almost any item if you have a reason for building it in that scenario. In General I recommend only 1-2 DMG Items (Look at the list above) into only Bruisery defensive Items from there (like DD, Maw, Titanic, Sundered, Steraks etc. alos in the list above)

This Safe Setup is focused on Abusing XinZhaos passive Sustain and Poke to outheal and slowly widdle down stronger earlygame champs, who you could not fight if you went the Aggro Build (i.e. Camille, Sett)

You go DRing + Full Scaling/Sustain Runes (mostly Grasp, Overgrowth, Presence of Mind, Double Scaling HP Shards) (vs Certain Matchups like Tanks you can go Lethal/Conq but still go the same scaling minor runes/shards)
You Rush Sundered Sky almost everygame as it synergizes with you BIIIIG HP POOL making you even Tankier giving you even better short trades and the heal + crit
1. Vs Tanks go BC Rush or Sundered Sky -> BC/Bork
2. I usually go Iceborn first Items if they have AD Top & Jungle
3. I go Sundered Sky -> Hullbreaker -> Titanic if its a game where I can splitpush well, like into shen or if they have bad sidelaners and we have good sidelaners
4. Otherwise I go Sundered Sky -> Eclipse/Titanic/DD/BlackCleaver

In terms of playstyle, this build is focused on short trades and then healing back up with passive and never running out of mana because of POM + DRING

1. with Aggro Setup you often win the lv.1 All-In if you skill E. Even if you just get an even trade if you can get back to the wave and heal back up from the minions you can win lane that way. Thats also why Ignite is so good because it means you often get uncontested access to the wave (because the enemy is scared) letting you heal up

2. with Safe Setup look for short trades (be careful when you jump in with E as youre playing vs strong Bruisers and you dont do too well now in extended Trades, especially if you have Grasp). You often start W and let stronger opponent slowly push you in early (trimming the wave where you can) and try to fight near your turret.
After your short trade heal back up from the minions and trade whenever you can with Grasp

Trade Combos:
(prepping your passive if you are going for a trade helps, as it gives bonus dmg)

• Main Quick Trade Combo: E->AA->Q->W (followed by extending or disengaging), with this combo your E and W will be on a similar cooldown and once you get some levels you can stall your Q autos out so you fully reset you E and then reengage
  
• Q Prep Combo: Q Minions twice->E->AA(Knockup)->W
  (this combo is often used to dive enemies and they have little to no counterplay)
  Does about 1/3+ HP of enemies earlygame, even more if you have ignite and passive stacked
  Q Minions Twice -> Flash -> knockup -> W -> AA+Ignite is often better to surprise finish opponents off, especially if you just used E
  
• Longrange Engage with W->E (Usually only good if you are coming from the front, If you are flanking the enemy team (which you should) you probably wanna engage with E or R->Flash)
  
• W Poke Followup Combo (highest damage (useful) combo for lane) W->Wait2Sec->E->AA->Q->Q->Q->W
  

Ult Combos:
(in general your ult does Current HP dmg, so it does more if they are higher HP, If you know that you want to fight someone to the death 1v1 you might wanna use it earlier rather than later, this ofc has tradeoffs like more ppl coming or disengaging and using it for turret dive combos etc.)

• R->W is really fast so the full main damage combo can fit in R for maximum damage:
  Full Fast Max Damage Combo: E->AA->Q->R->W or long Combo: W->Wait2Sec->E->AA->Q->Q->Q->R->W
• E->R mid-dash especially good when diving for maximum burst as you skip the R animation
• You can R->Flash into many people in teamfights, this pairs especially well if you R->Flash->W->E or R->Flash->E.
• You can R someone into a Wall to stun them without knocking them back far. This is especially useful when towerdiving in toplane letting you R(into Wall)->W hitting both parts of your W while they cant react letting you followup with E if they flash afterwards