Maybe checkout Pixelfed, which is (from what I gather) similar to what instagram was 10 years ago

Oooh they were talking about Image filters…

My brain defaulted to keyword filters etc

Wait how do I use the cat filter

Not sure the problem is your sister, as much as it is your conflating the fediverse with Lemmy. As others have mentioned, the appropriate response here seems to be a link to Pixelfed rather than frustration at someone using social media differently than you. You wouldn’t try to force an IG user to join Reddit if that’s not their thing.

There’s a keyword filter and an NSFW filter

I didn’t expect to see my boi Thurston today. RIP you crazy son of cat.

It has a nice filter where it excludes people that roll their eyes when they hear words like “federation”.