How Do I unlock The Sim card on my iPhone 11

if you forgot your sim card pin code and got it locked read

Use a SIM PIN for your iPhone or iPad - Apple Support

scroll down to the section "If you forgot or don't know your SIM PIN"

If you’re wanting to use a different SIM card than your carrier and the device is currently locked you will need to contact the carrier and see if they will unlock it. Carriers have different criteria to do so. If you just mean you had a sim pin on your SIM card and don’t remember it follow the info In the previous response