On Thursday, Aug 13, 2026 I gave a presentation to the M365 User Group here of Washington, DC. Here is my PowerPoint presentation in case you want to see or use it.
To summarize: list formatting, column formatting, and form formatting are done in JSON behind the scenes. In advanced mode, you can customize the JSON code directly to achieve some pretty impressive results. There is a repository of examples for you to copy and paste from at Github that give some impressive results instantly, so I wanted to introduce these.
Upon reflection, I should have went in a different order for my presentation. I should have went straight from formatting a column via the GUI to the advanced formatting examples of column formatting from Github. Then, discuss formatting the entire list with examples from Github. Now introduce forms. Formatting the forms (reference the Microsoft basic instructions page) should then lead to a wrap-up of the various form examples (mainly nice headers) from Github. Live and learn.