iPhone is frozen

Hey, I was just on FaceTime and my phone started to act slow. I locked it n it didn’t lock. Now since I’m off FaceTime, my phone won’t lock when I pressed the lock button, I can’t open setting nor reset my phone. I can’t shut it down or nothing. I can’t even force a shut down on it bc the slide to shut down isn’t even popping up. I can’t open any apps or even ask Siri to do it. This is a big problem