Generally, apps work smoothly in the iPhone 13 but in case if an app misbehaves or is unresponsive, you can force close it. It is very easy to force the app to close.
To close an app in iPhone 13, you need to launch the app switcher screen
Swipe upward from the bottom edge of the screen of your iPhone and pause in the middle of the screen, then lift your finger
Now a gallery of thumbnails will appear that represent currently open apps on your iPhone 13.
To browse the apps swipe thumbnails left or right .
When you find the app you want to close, quickly flick the thumbnail upward, toward the top of the screen
The thumbnail will disappear, and the app will be force to close
If you are still having trouble with an app after forcing it to close try restarting your iPhone 13