Will iMessage on the iPhone still work even if the iCloud storage is full?

Will iMessage on the iPhone still work even if the iCloud storage is full?

Most likely yes, even if your iCloud storage is full your messages which only take up a small fraction of your file sizes won't cause iclouds storage to be overflowing. Another thing to take into account is that they're mostly stored on a separate server but backed up onto iCloud drives. So don't worry about that! I've has my storage full for god knows how long. Hope this helps!

It should, but you may get a warning about storing any media you may get through it.