Anime is computer edited 2D cells drawn on tablets for foreground and background and layered. The 3D work is limited to certain scenes.
3D animation can be scaled up and down, but it's not hand drawn and converted to raster images like the 2D cells necessarily.
I imagine with anime they just agree on a resolution for all the rasters and plug away at it, because they're under insane time/budget pressure.
The painted backgrounds who knows.