Could you provide what equipment/OS/version you're using? If you have the same phone as someone here, they could give you step by step directions. I don't post from my phone, so I can't help, but I do now the native images from my iPhone are always multiple megabytes (I import those to my MacBook and resize using the native Preview program; I only post using my MacBook).
Same here, even my 2019 Samsung phone takes photos in the megabytes. Raws are 25ish, and jpegs are 2-3ish
