I forget my passcode on my iPhone

You will have to reset the passcode. You will need a computer to complete the task. You can reset your passcode by following the instructions in this article by Apple ➔ How to reset your passcode on a disabled iPhone. You will need a computer for this task and all your data on your iPhone will be wiped clean in the process.

Axel F.

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

Your iPhone 11 is later than an iPhone X so the article applies to your model as well.

Axel F.