expand on something
expand upon something

The building was expanded on its west side in the 1940s.

Today the Hospital is being expanded on the same site.

I would like to expand on a couple of them.

I am going to expand on some of these points.

I'd like you to expand on this point because I'm not sure what you're talking about.

"Perhaps you can expand on that answer for those of us who are not human."

In 1894 the science and art school opened to expand the training on offer.

I would like you to expand on it a little.

I would like to expand a little bit on that point.

I will not expand too much on this subject, as others have already done so before me.