My iphone 11 turn to pink screen. how to fix it?

Check if it is a temporary screen glitch, by performing a "forced" restart of your 11, as per these instructions:--> Force restart iPhone – Apple Support

If the issue persists, I suggest that you make an appointment (*) and have your device inspected at an Apple Store or AASP (Apple Authorized Service Provider) among this list:--> Apple – Location Selector. After checking it out, they'll give you all the available options.

Regards

Giulio

(*) You can do it:

• Online:--> Genius Bar Reservation and Apple Support Options - Apple;
• Contacting a local Apple Store or AASP among the list provided above;
• Using the "Apple Store" app, available and downloadable from AppStore.

rica196 wrote:

I don’t know how

What can't you do?

I think his suggestion is correct.

Best of luck.

Giulio