Pubg lag

Why my iphone XR lagging while playing pubg. I bought my phone for Rs 52500 Indian rupees. Then what the **** is this? An apple product lagging in game? What the ******** is this? Please help us. Please understand our mental pressure. A premium brand getting lag on games.? Then how should we purchase more apple products? Please fix this problem. We trust Apple, don't make it false..please