How large (sheet size) and how crisp (dpi) do you want to go? What resolution do you start with?

@Annie Annie thanks! Okay, my guess is that using resample: preserve details (enlargement) at reduce noise level: 50 in Photoshop ought to do the trick for you without needing to make any other adjustments. I go from about 1728px wide to 4677px wide using exactly those settings, and with that have printed A3 posters that people are absolutely delighted with (and confidently offer to go to A2). 👍

maybe .. https://printshrimp.com/blogs/poster-guide/how-to-create-posters-for-print-on-demand

Congrats!! 🥂 What Mihai said. 😁🙌

This one actually started off as a hand drawing and it was really gratuitous. I used Gemini to soften the weirdness I had made, but her legs are still the same as I had drawn them.. https://barttheraccoon.etsy.com/listing/4475642718

Personally, I'd recommend this as it's a nice way to boost visibility and traffic to your store, if you need this. It's worked for me, and about 25% of my sales are digital, meaning I'm not losing on the higher profit from posters while "casting the net wider" for my store at the same time. If you don't mind sharing, what's the link to your store, please? Perhaps I could take a look at your store and share some insights, especially as my last response to your separate question here might sound a little confused. :)

@Tim Crowley thanks for asking! Absolutely a separate listing: only separate downloads-only listings are likely to get you selling that kind of product (relatively) trouble free. You’ll see at least 2 folks here who have bundled downloadables with physical items, and they’ve run into troubles directly resulting from combining the two.