S9+ never able to send MMS images unless it seems photo is tiny.

Take photo try to send mms.
Phone attempts to convert to mms and reduces file size
Message saying failed to send

What I've found is if instead of using gallery to pick the photo instead I go to image shrink app and then choose the photo and set the size to 640 x 480 for example it will send.

Is there any way to configure the stock SMS app to choose a certain shrink size when it handles MMS?

511kb is this one but others have been smaller
2degrees have sent me configuration text and that's been installed fine.