If I have an iPhone 11 how do I Reser it if I forgot my code

Remove the passcode on iPhone X or later, iPhone SE (2nd generation), iPhone 8, and iPhone 8 Plus

1. Make sure that your iPhone isn't connected to your computer.
2. Press and hold the Side button and one of the volume buttons until the power off slider appears. Drag the slider to turn off your iPhone. Then connect your iPhone to your computer while holding the Side button. Keep holding the Side button until you see the recovery mode screen.
3. 
4. If you backed up your iPhone, after you remove the passcode, restore your data and settings.

You will need to follow the instructions in the blue link above your name on this page using a computer. Later you can restore your data from a recent back-up.

This video may help...