I've been trying a few options and came across 3 that are worth checking.
Upscayl runs directly from your PC (no constraints, no account data) and uses your GPU to uplift the images, does a decent job and doesn't change things, it only raises the resolution and applies a series of techniques to make them look better.
Stylar does require an account, the images have limitations and do have a watermark, however it allows you to have a grasp on what AI can do, it can remake your content provided the input is correct, the outcome can easily be changed in photoshop, you can for example remove the watermark and you can use the 1st tool (upscayl) to increase the resolution. You are not bound by the limitations of the tool.
Krea, this one is probably the best, because it can reimagine your image, you can set it so it's similar to your input but still give AI the ability to create content, which will surpass a simple upscaller, this tool ofcourse is limited to 3 minutes per day on free accounts, but 3 minutes is enough for you to get a grasp on what it can do
Take an example
I recreated this scene a while back:
I did a few skins, changed the look, used some bloom ingame and did the screenshot on PSO v2 of all things
This is what krea did, remember this is the default settings, one can make it more towards the original image and some can just ask the AI to go crazy and re imagine things
I'm sure with some time one could just upscale the textures or even use krea to add some detail to the images, just enough so the image is super sharp and no weird bluriness