Battery

Aashish739,

Try checking your Battery Health in Settings > Battery > Battery Health. Because I'm not too sure what generation your iPhone is, I recommend making sure your phone is installed to the latest update before you check your Battery status.

Try disabling "optimized charging" option in Setting>Battery>Battery health.. and tapping there.

When done, restart your iphone, and let it charge all night long.

For any furter question about that, take a look at this User Tip:--> When to charge your iPhone or iPad - Apple Community

Regards

Giulio