League of Legends (LoL) Question: I have 6300 IP

Maybe wait and play champs in the free rotation until you find one you like instead of blowing your hard earned ip on someone you have little to no experience on.

I recommend Fiora, she is very strong in early, mid and late. She can carry the game and deals high amounts of dmg (later on her damage is mostly truedamage)

before buy a champ, look and the guides from him, you must know how it is played.
if you have the champ to cost 6300 i reccomand you:
Top - Illaoi
Jungle - Rek'Sai (is meta)
Mid - Ekko (i really like this champ, is funny to play, and have interactive replies with his build items like guardian angel)
Bot - Xayah if u have an duo or else Lucian is meta too, or Jhin who is intersting cause his weapon system is unique in the game, you could if want go full ad/letality and single critik item be a infinity, cause the 4th attack will be 100% a critik.
Support - Rakan if u have an duo or else tahm kench or nami (both are very useful).

Top > tryndamere
Mid > Fizz
Jungle > Lee sin
Adc > Lucian
Support > brand

Any role you want to play in particular? If you're looking for an ADC, I'd recommend Lucian instead of Jhin.