iPhone are the worst device to play bgmi and android are more worst then iphone but if you play pubg mobile global then the different changes android give more fps then iphone btw I am talking about iphone 15 pro vs Samsung S23+ I have both the device so I checked it and it was true
Bhai don't give wrong advice for now in 2023 if you have budget then go for 13 and if you have tight budget go for 12 please don't go for 11 it is no worth in 2023 because of its 720p display and smaller battery push the budget and go for 12 or 13 both are good for now
It's m4 glacier level 5 if you are taking about hit effect if you are taking about aim you can try low gyro sensitivity and practice on that for better accuracy