Such as?

Pretty much anything that Trump is running roughshod over.

Codifying and clarifying Presidential criminal (and maybe civil) immunity
Giving some teeth to the Judiciary
Limits on impoundment
Pulling independent agencies (USAID, Natl Institute for the Arts, etc.) further away from Presidential control
Tighter Congressional control over declarations of war and emergencies
Resubmitting the ERA

I'm sure there are more ideas.

Constitutional amendments are darned difficult to get passed.

Yes, they are. But national crises seem to be a uniting force to get amendments passed. Civil war bore 3 or 4 amendments. The robber barons of the late 19th and early 20th centuries brought a couple, as did the Great Depression. Civil rights era gave us a couple.

Of course, this will only happen if the GOP figures out what they have unleashed on the country, or if a new conservative party arises to replace the GOP. If neither of those happen, no amendments. And possibly the major re-creation of the USA into something post-constitutional, up to and including a dictatorship.

--Peter