Most photos are ruined because they're under unnatural light. There are plenty of online tools for correcting images, but in this example, I used the Preview app that comes with MacOS. Below is a before/after photo borrowed from the forums:



The "after" photo shows more detail and looks more natural.

To correct, I started with the Temperature slider. It's color correcting the warmth of the light. Next, I move to Shadows, which will help bring out features in the subject. Next, I'll increase exposure. Most indoor photos are underexposed and the subjects look bland-ish. Adding light will make the photo "pop" better, especially in social media. You may have to fiddle with contrast, but that's the last resort since it dramatically shifts the image. Finally, take a look at Saturation. It adds redness that may be missing from people's faces and can make backgrounds look more accurately colored (especially blue and red).