Use the site bigjpg.com, which is free and does not require mandatory registration.
The service is based on a neural network with special algorithms for image enlargement with noise suppression.
The image size limits are 10 MB and 3000×3000 pixels, and zooming is only possible by 4x. But after registration, it increases to 16x.
The photo below shows a comparison of scaling an image from 256 pixels to 1024 pixels in Photoshop and through the service bigjpg.com