Social media sites use their own rules how they mangle photos. They need to try to keep the storage costs low enough to maximize their profits.
You must be somehow important to the media company (for. ex. the biggest owner) to force them behave as you want. Social media companies do not care of ordinary punters, they are only food and the data mining plant.
But you can optimize your images so that their automation causes the least amount of damage (=do not exceed certain dimensions, have certain aspect ratio, have more contrast than needed at your own PC, do not compress it to low quality before uploading) Search for guides. Here's one:
https://www.softwarehow.com/upload-quality-photos-instagram/
and here's another: