I spent several hours on a new project and kept hitting walls while learning the Settings API with WordPress documentation that seemed to present outdated examples that would not work with the current version of WordPress 5.5.
After trying three times using the documentation and two other documented tutorials, I wasn’t getting anywhere. Then I found this Settings API generator and it worked right away. It provided a starting point, which I modified until the final was to my liking. I also used his Meta Box generator and modified that too. I think it should be linked to the WordPress documentation that has outdated links from seven years past. Thank you so much for this tool, Jeremy Hixon!