I read a post on a website that stated that approximately 10^-36 seconds after the Big Bang the Universe expanded disproportionately to the size of an orange. Is the Universe still expanding at the same rate, and if not why ?

Google 'big bang inflationary models'.

Or do a search on this forum.

I'm sure Mordred has posted relevant links.

It depends on the inflaton model. We know it needs to expand 60 efolds to solve the horizon problem. However the exact number isn't known and there is roughly 70 viable inflation models