In iOS 11 the Control Center has been reduced from the two or three pages in iOS 10 to
a single page in iOS 11.
AND you can now customize Control Center to a certain extent in Settings >
Control Center > Customize Controls. Most notably, you can add a
variety of Apple-provided controls.
Although you can remove a few default controls, others are fixed:
the networking platter, the media platter, Orientation Lock, Do Not
Disturb, Screen Mirroring, Brightness, and Volume.