You missed nothing. It was never mooted by Apple as a feature, nor a potential one. The rumour mill suggested it would be there but we know what a load of crap that’s been this year.
Maybe it will get added in iOS 15.1 or 15.2?? Can’t see why Apple won’t do it, unless they don’t want the hit to battery life. Because obviously they don’t want the user to make that choice …..