Can someone be flexible in their polyamory? There are some partners I’d rather be in an open relationship. And then there are potential partners I’d rather be monogamous with assuming specific needs are communicated and met.

You answered your own question! Of course someone can be flexible - you’re living proof of it!

People are complex. Relationships are complex. Almost no one fits perfectly into every single box - there are nuances and quirks and qualifiers to everyone’s identity.

As in all things, honesty is key. Honesty with yourself and with your partners about what you want and what you need.