Google Pixel and Samsung phones have taken over power menus by forcing Assistant and Bixby on you. You can change them back to power menus.

Quick Answer: To restart your iPhone without the power button, go to Settings > General > Shut Down, then slide to power off.

Phone manufacturers: please give us the power button back I don’t want to talk to Siri, Google, or Bixby. Please just make the power button do what it’s supposed to do.