Might be a carrier issue. Though a few things you can try is
1) go to settings>apps>messages>clear data cache
2) clear system cache in Recovery mode (google how to get into recovery mode of your device)
3a) throw your phone out the window of a moving car (just kidding)
3b) contact your carrier to see if they see any issues on their end.
Do you have the same behaviour with the Samsung Messages app?
Are you using RCS in Google Messages? (have you tried turning it off if it's on?)