Upscaling hd to 4k with keyframes animations everywhere

Hello, sorry if this question has already been asked before, but I couldn’t find a topic that matched my issue.
Here’s my situation: I animated using a 2D animation software (TVPaint) and exported many layers in 1920x1080, as well as still images imported from Photoshop. I then assembled everything in After Effects, adding lots of animation keys (with rotations on all three axes, precompositions, etc.).
However, I now need to upscale everything to 4K. This means I have to re-import my TVPaint animation frames at twice their size, which alters all the animation keys in After Effects. Using CTRL+ALT+F to adapt to the new format doesn’t work because I sometimes intentionally scaled elements beyond the frame.

Do you have any idea how I could scale my entire file to double its size, while also doubling all the animation keys across all layers?

Thank you, I hope I’ve explained it clearly enough...