In the latest Adobe Photoshop and Camera RAW update, a new super-resolution enhancement feature has been introduced, and it actually works surprisingly well!
Photoshop's new super-resolution feature will take your photograph and double the resolution of the width and height. Then, it will fill in the additional required pixels with AI to maximise the resolution to twice the amount. This, essentially, means that your image will be four times larger over a square area.
This feature is found in Camera RAW (the RAW image plugin for Photoshop) and only works on DNG raw files (or camera-make equivalent).
Once opened, make sure to make no adjustments to the image first. Then, you can head over to the image, right-click and scroll down the options until you find the option called "Enhance".
Photoshop will then proceed to process the image into a far higher resolution image, based on the original amount of pixels the camera used to create it. So, for example, if your image was 4000 x 6000 pixels as standard, the enhanced feature will output it to 8000 x 12000 pixels, which is twice as large, but four times the physical area.
Take a look at the video below by YouTube channel, Photoshop Cafe, on How To ENLARGE your photos 4X. New in Photoshop, Super Resolution tips and tutorial.