WIBTA if I just blocked this girl that consistently messages me and sends me stuff, even when I don’t engage?

So there’s this girl I know, and she’s a few years older than me, we went to the same middle school and have mutual friends. She has learning disabilities and autism. So I get why she may not understand that what she’s doing is annoying- but how do I say it without being rude?

I understand she’s trying to make friends, and I’m friendly with her online and have been for years. However she constantly sends me “sister” memes and “share this with your bestie!” stuff, when it’s not like that and honestly gets kind of annoying because it’s nearly every day.

What should I say/do?