Not on the same day. It is physically possible under a narrow set of schedules, but it is a poor trade and we would talk you out of it.
Crossing the border costs two to three hours round trip in transport and waiting. On a day with seven or eight hours at the falls, that is a third of your time spent in a vehicle and a queue. You would be swapping most of the Argentine park, which holds the majority of the walkways and every up-close viewpoint, for a shorter visit to a panorama on the other side.
Some nationalities also need a visa for Brazil, which is not a thing to discover at the border on a day with no slack in it.
The one case where it makes sense
If you are flying onward from IGU, the airport at Foz do Iguaçu, continuing to Rio de Janeiro or São Paulo to see someone, say, then you are crossing anyway. At that point the Brazilian side is on your route rather than a detour, and it is worth building the day around.
For everyone else coming from Buenos Aires for the day: stay on the Argentine side. Devil’s Throat, the Upper Circuit and the Lower Circuit are what you came for, and there is comfortably enough in them to fill every hour you have.
