Face ID is not available

Please take a look at the following article, there may be something wrong with your TrueDepth camera ⇢

If an alert says Face ID has an issue on your iPhone or iPad Pro - Apple Support

We would need more information, starting with model of iPhone you have and what version of iOS it's running, before anyone could offer specific advice. Start here:

If Face ID isn't working on your iPhone or iPad Pro - Apple Support

and post back with full details if nothing in that support article helps.

Regards.

If none of the steps in the support articles we've both linked to help, contact Apple Support for further assistance.