Can not use iPhone due to Guided Access

After I accidentally clicked on **Guided Access**, my iPhone became unusable. I tried to shut my iPhone down but it won't do anything after I slide the bar to turn it off. I have an iPhone 11 and just updated to iOS 16. Apparently, I enabled **Guided Access** at some point with 3 clicks on the side button (or maybe it was there already?) because I don't even know what that is. Yesterday, I added in **Accessibility**, the task to change the screen's brightness with 3 clicks of the side button. When I did 3 clicks, it asked which one I wanted: **Guided Access** or change brightness. The second one worked fine but I did it again with **Guided Access** to see what it does and now I just can’t do anything with my iPhone, not even restart it.