It may be that you're not saving the pictures as jpeg's.
Open the Camera->Settings->Picture Formats->Turn off "High Efficiency Pictures"
Now take a pic and try to send that. The pic will be resized by the Message app and may lose some picture quality.
Galaxy Fold 5 512g(VZW), Galaxy Book (original, VZW), Tab S8 Ultra, Tab S4, Galaxy Watch6Classic 47mm(VZW), Galaxy Watch5Pro(VZW), M8 Smart Monitor