Nice I will have to check this out, control center is definitely a great little overlay but I haven't reliably figured out how to add things to it. I will investigate further.
For general information have a look here [0]. Also be aware that elements in the control center might even offer additional functionality, e.g. like setting the brightness of the flashlight. In this case instead of just switching the flashlight on by a tap on the button, keep the flashlight button pressed to bring up a slider to set the brightness. Just play around with the other control center elements to find out what is possible.
[0] https://support.apple.com/guide/iphone/iph59095ec58/ios