Here were/are 3 things that "reset" the iPhone without requiring restoring anything:
- Simple Restart: Hold down the Volume Up and the Side button. Slide to turn off. Turn back on with Side button.
- Purge RAM: If you don't have a Home button, go to Settings->Accessibility->Touch->Assistive Touch->On. Unlock your phone. Next, in quick succession, press the volume up button, then press the volume down button, then hold the lock button until a shutdown menu appears. Hold down physical or virtual Home button and enter your passcode when prompted.
- Force Restart: Press and quickly release the volume up button. Press and quickly release the volume down button. Press and hold the side button. When the Apple logo appears, release the side button.
They removed #2. My guess is that they removed this because too many people found out about it and were doing it when they shouldn't be.
If you're having problems with your iPhone, try simply restarting it. This should be a very rare thing to do. Many people never restart their iPhones without issue except for when system updates occur.
When your iPhone freezes up, you may not be able to restart it as described above and a Force Restart may be required. You want to avoid doing this unless it's necessary, and never do this as a habit.
You'll notice they didn't make purging ram or force restarting easy, just like there's no button to tap to Force Quit all apps. There's a good reason for this.