Hi!
I just got done on apple support, because I was having so many issues after my phone updated last night. First, make sure your phone is completely backed up, and then try restarting it normally. Press and quickly release the Volume Up button. Press and quickly release the Volume Down button. Then press and hold the Power button until the device restarts. After it restarts, check to see if the issues have improved, and if not, you most likely will have to erase the phone and restart it with your recent backup or as a new device.
Hope this helps!