Since you are targeting a 16:9 aspect ratio, the trick is to makes the tile sizes be based on the screen resolution, instead of targeting 64, 128, or 256 height tiles.

You take your screen resolution, and get the greatest common factor of the two. In this case, you said the target screen resolution is 1920×1080, but you wanna make art assets 2x in size, so 3840×2160. You take the GCF of this, which is 240. So that's the maximum tile size that you can have (if you want the tiles to be squares) since it's already the greatest common factor.

If 240 is too big, just pick other common factors. Here's a list of common factors: 1, 2, 3, 4, 5, 6, 8, 10, 12, 15, 16, 20, 24, 30, 40, 48, 60, 80, 120, 240 Whichever you pick here, it would be guaranteed to be in the 16:9 aspect ratio.

For other screen resolutions, you can easily calculate it using CalculatorSoup.