How to fix FPS drop in PUBG Mobile on iPhone 16 Pro Max running iOS 18.3.2?

I recently bought iphone 16 pro max 256gb. while I play pubg mobile on it the fps drops badly and the game becomes choppy. In game settings is fine. It runs smoothly on 90fps than 120fps. the software is up to date currently running IOS 18.3.2. Any solution?

[Re-Titled by Moderator]