Apple TV - full screen

I have several Apple TV 4Ks. When watching something that is displayed in 21:9, so black bars at top and bottom of the screen, I used to be able to double tap (or click, I forget now) the scroll pad at the top of the remote and the image would 'zoom' to fill the screen top to bottom, so no black bars. This was great as I like to watch a full screen and not reduced size due to wasted black areas at the top and bottom.

I am NOT talking about stretching the image. Just increasing its size to fill the screen and I am fully aware that means some of the image at the sides will be lost, but I do not care. I realise there are some to whom this is anathema and they cannot abide not seeing 'what the director intended' (even though the director might have actually intended something else). Ok, that's their opinion, but I don't happen to share it and this is not a debate about the rights and wrongs of our viewing preferences.

No, this is about how to achieve what I once could with my Apple TV.

In Settings I have set 'Tap to Zoom'. Seems to do nothing. I keep trying it, but has no effect I have ever seen.

There is a Zoom feature in 'Accessibility', but when I checked, that only offered a minimum of 1.5x which was too large and anyway the image too easily moved around the screen.

This really should be simple for those of us who want the full screen of our expensive TV to be utilised. It could so easily be done and indeed was possible, but then it was taken away. Why?

I'm hoping though that it's simply a misunderstanding and there is a way, but I haven't yet figured it out.

To clarify, I'm not wanting to stretch any image, nor expand a 4:3 to fit a 16:9 screen as the top and bottom of the image is likely to be important. No, I am only enquiring about widerscreen formats than the physical display, e.g. the common 21:9 film format on a 16:9 widescreen TV. It used to be common that such formats would be broadcast in a size to suit the display and I don't recall EVER thinking I'd missed something that was on the outer edges, because filmmakers tend to locate the 'action' more in the centre and extra wideness of the image is used to create the sense of space. So losing the edges means you generally miss nothing of importance. If on the very rare occasion there is something you want to see, then the simple gesture used to expand the image could be used to shrink it back to letterbox again so you'd see everything. Then another simple tap (or double tap or whatever) would expand it again. That's why it needs to be a simple method of switching.

None of this needs to affect those who are convinced they are gaining something from having big black bands top and bottom. Those users simply do nothing and revel in the blackness of those bands, top and bottom of the screen, devoid of any image. 🙂

But is this simple switching still possible? How?