Is English your second language? If what I think you meant your question should be "Can posting pictures of someone be a sin?" The answer is "It depends". Did the person give you permission. Is the picture intended to harm either the person in the picture or the person viewing the picture.

there’s a bunch of stuff that’s supposedly a sin that religious people don’t take note of. they just pick and choose which ones to follow and which ones to tell other people they’re a sinner for. example: eating shellfish is a sin. fornicating before marriage is a sin. wearing mixed fabrics is a sin.

it depends on your motivation. if it was to cause harm or mockery to them then yes it is a sin.

Without their knowledge it’s more weird than a sin. But if they know about it then hoorah

I remember when I was first learning English.

If without permission and makes that person look bad

Yes and now you must do 666 Ave Marias