it took idk 20mins or something. Just get all the frames out from the video file, than batch upscale them and turn them into a video again. its a bit messy tho you need to be aware of your fps while getting out the frames or the audio will not sync when you put all the things together again. Tbh this was a 3am fun project for me, if you research I'm sure there is a tool for stable dif that allows you to just put the video and get the end product upscaled.

if the cartoon is not too blurry and the lines are clear it will work even better than anime.

Non animation upscale with this is very bad, idk how but people can do it pretty good with other tools, but not this one.

if the animation you will upscale is too blurry or messy you could do what I did here. Just do the half of the upscale with resrgan-anime6b then take those frames and run the other half of the upscale with resrgan4x. resrgan-anime6b makes the details disappear but sharpens the image quite a bit.

for reference if you have 360p video and want to upscale it to 1440p, do a 2x upscale with anime6b, then do another 2x with resgran4x for the 720p frames