Hi YellowtailMama,
Welcome to Apple Support Communities! Sounds like you are getting an error when trying to send photos or stickers in Messages on your iPhone 11 running iOS 14.6, do we have that right? Is this only happening with a specific contact or with multiple? Are they able to send you any photos or stickers? Since noticing this issue, has the Messages app been closed out? You can close it completely and then restart your iPhone.
Close an app on your iPhone or iPod touch
Restart your iPhone
You can also try the steps in this article to troubleshoot: If you can't send or receive messages on your iPhone, iPad, or iPod touch
Hope that helps!