How to restore color and sharpness of old photos

[satimis]

Hi all

Please advise how to restore old color photos.

I have old color hardcopy photos converted to digital copies using an android phone connected via an USB cable to Ubuntu 24.04 desktop PC with remote desktop. This setup works for me without problem. Copies of 3 digitized photos are attached here as example.

I expect to retouch them adding colors on the fade colored photos as well as making the photos more sharp . Please advice.

I'll not print the edited photos but using them building digital slideshow only.

Thanks in advance.

Regards