Most carriers impose limits on the size of a Multimedia Messaging Service (MMS) message (i.e., messages with images, GIFs or attachments). For example, one carrier allows image attachments up to ~1.2 MB and videos up to ~3.5 MB.
Some messaging apps or platforms (e.g., Google Messages) may enforce internal attachment limits (for example, it may refuse files over ~100 MB or convert large attachments into links).
If your file exceeds the receiving carrier’s limit, it may be rejected, compressed to a lower quality, or simply not delivered.
Also note: standard SMS (text only) does not support attachments; once you add an image or media the system moves to MMS or an RCS-type send.
There is a light limit of 16MB file size.