If you insist is a soft agreement given after being pressed. Oh, if you insist.
It accepts while making clear the acceptance was not sought, which is why it is used for a second slice of cake. The tone decides whether it is charming or grudging.
1phraseif you insistA soft agreement given after being pressed.
“Another glass, then, if you insist.”
if you insist is a phrase.
Practised in Small Talk & Everyday Phrases