How can I disable the auto-lock settings on my iPhone 12?

in iOS18 om ny iPhone 12, the auto-lock feature are limited to 30s or 1min timers, and is unable to turn off, this makes it impossible to listen to a video while doing a task away from the phone, as it will lock the phone and the video stops.

Please add the option to turn this feature of, if it is possible allready, make it simpler to find, iOS settings menu is a dissaster.

[Re-Titled by Moderator]