Is there any way of resizing without losing all detail? I drew my contest entry at 2500x5000 and, no matter what method I try, I can't seem to stop the details from turning into a blurry mess. Is there any way of keeping at least some of the clarity? (I use Clip Studio Paint btw)

unfortunately, you’ll probably need to start over. I recently tried out a new program and was working at about half of your size, and the wearables were sharp and jagged and terrible.

I generally work a hair larger than double the display size (255x510) with a small brush (cover pencil at 2.1 in painter 11 or studio pen at 6-7% in Procreate) and that gives me good results. You could go a little bigger and still be fine, but I think once you hit 4 digits in canvas size, you’re gonna lose all the detail.

What you can do now is resize what you’ve got to the point where it still looks okay, and then just sketch over that to preserve your details. Then keep resizing and re-lining that until you hit 250x500 canvas size and then finish your image. It’s tedious, but then you might be able to salvage the design rather than completely starting over. Good luck!

The expression of an artist who stayed up to 5am for naught.

Ooh, yeah, that is not going to resize well at all. :( Bean's got great advice for sizing down, although to offer a slightly different perspective I used to work at 250 x 500 but didn't like how pixelated things looked while working on them (what can I say, I love the zoom feature) so I now work at 500 x 1000 for the majority of my larger wears (bgs, large clothing items, etc). So you might be able to make it work at that size. I have noticed that eyes/lips/small detail things do tend to work better at the 250x500 though since any pixel shifting during resize can really change the end result on those. Hope you're able to salvage your design!

I also highly recommend merging your layers before you resize so that it's one 'flat' image and the layers cannot skew when they're being shrunken down.

(And I'll also agree that the size you're working at is way too large. I don't recommend anything bigger than 4x the final size for these, and even that is sometimes too big for some artists.)

[edit] it helps to save a second file of your image before merging if you're not used to it just so you don't accidentally save over the non-merged file and not be able to come back to it later for edits or recolors.