Open Settings
Go to Apps
Select Background apps or Installed apps
Choose the app you want to stop
Open Advanced options if available
Set Background app permissions to Never
Turn off Let this app run in the background
Go to Privacy
Open Background apps
Turn off Let apps run in the background
Open Battery settings
Enable Battery saver to limit background activity
Open Task Manager
End unnecessary background processes
Disable startup apps in Task Manager
Restart the device if needed