Is it possible to make black bars that turn the screen into a 4:3 ratio on all screen sizes?

[Ryanthemudkip (Mudkip)]

I’m making something that would fit in the era where 4:3 television was a thing. Is there a way to do this?

[CoderHusk]

I suppose you can get their pixels are find the delta ratio and set the difference to that by subtractively doing it to put like black frames dependent on what axis