In theory, if you use the main gameplay character and not a copy, the camera is blended.
If you right clic on your character track, you should see “convert to spawnable” if your character is possessed.
In our project, we have a camera manager in C++ to blend on tick…
But in the UE camera examples the blend is effective and the SetViewTargetWithBlend is working.
Try to set the blend at 5s so you have time to see if it works.