enlarge on/upon
— phrasal verb with enlarge us/ɪnˈlɑrdʒ/verb [ T ]
to speak or write about something in detail or in more detail:
I was asked to enlarge upon my theory.
enlargement
noun [ C/U ] us/ɪnˈlɑrdʒ·mənt/
[ C ] My mother had an enlargement of the photograph framed.
[ U ] The new budget would have resulted in enlargement of the deficit.