If you base it on 4k as a mainline resolution - just like with textures - you can always reduce with minor artifacts to any power of 2 value.
Until about 256 when it probably becomes unusable.
When making pixel art you have to set whatever dcc to Nearest when scaling though, as bilinear and, well just about any other interpolation will “blur” your pixels instead of keeping them as pixels.
You could even count every pixel as 4 pixels or 16 pixels in order to maintain the “blotchy” pixel style at higher resolutions. Depends on the end goal really.
Must it look like a pixel crock of ■■■■ at any resolution? Yes: have a “pixel” be more than a pixel.
No: Use all the pixels.
Like with the DCC programs you can set the unreal mip system to use the proper filtering by modifying the texture settings.
This could be important too.
Going with mainstream art examples
You can consider GGX 3 as a double resolution pixel art work.
And SF3 as a regular resolution pixel art.
That said. Unreal isn’t the engine to make a pixel art game. Use something better.
Godot for instance.
Pixel based engines that allow pixel edge detection by design will be a lot better over dealing with the ■■■■ you have to deal with in Unreal, where you can even sort the priority without moving stuff in 3d space.
You can look it up but double res means you make something 2 times as big and let the engine scale it down to half its size with a filter at runtime, allowing for much more detail.
Particulalry because it won’t necessarily scale down on higher resolutions, offering the original artwork displayed based on the resolution used by the system.