I cannot turn my iPhone 13 off! How do I turn it Off? The side button doesnt do it!

The side button on its own will not turn off the iPhone 13. You have to press the side button and the volume up button and hold until you see the power slider.

It is stuck and I can not get it to work

See the following from Restart your iPhone - Apple Support

How to restart your iPhone X, 11, 12, or 13

1. Press and hold either volume button and the side button until the power off slider appears.
2. 
3. 
   
4. Drag the slider, then wait 30 seconds for your device to turn off. If your device is frozen or unresponsive, force restart your device.
5. To turn your device back on, press and hold the side button (on the right side of your iPhone) until you see the Apple logo.

If the device is frozen and you cannot turn it off, follow the steps in this link, Force restart iPhone - Apple Support

This is not working at all.