They probably should have the option to change the tab size on an open file, but my point is, why wouldn't you have autoformatting on for YAML and JSON? You have a preference for indent size, and you want the same for every file, barring an edge case.

"languages": { "JSON": { "tab_size": 4 }, "JSONC": { "tab_size": 4 }, "YAML": { "tab_size": 4 } }

Edit: Yeah I see your point when you are not in control of the project and have to stick to someone elses style, I guess that only seems like an edge case to me, but could be normal for other people. In that case you would want a convenient way to override your formatting settings, like an auto detect indent button that only applies to the current open file.