My goto with any dialogue questions are Mamet and Sorkin and how to solve the problem has a lot to do with the structure of the scene. Assuming dialogue needs to sound natural, declare stakes (Characters are speaking because one wants X from another character) and use subtext (via reference and foreshadowing), then I'd break it down into structures:
1v1v1
Each character is there for their own reasons and they're trying to get something out of another character with no character seeking information from the same person as another character (1 wants something from 2, 2 wants something from 3, 3 wants something from 1).
Lots of tags, but ideally you can use pronouns to your benefit (2 men, 1 woman, etc).
Power dynamics are super important in this style and can and should shift as short term alliances/overlapping wants form and break.
Oftentimes these scenes work as like 1v1 with 1 on the sideline for a bit, then the active 1v1 shifts, then again, then again. Dialogue tags work, but emoting and motions can do some heavy lifting.
"blah blah," he said.
X rolled her eyes.
"Blah? No, blah blah."
"But blah--"
"No, you blah!" she hissed, her eyes flashing dangerously.
"Woah, blah blah," z rose, arms outstretched in gesture of placation. "We all want blah blah."
"I don't want blah."
"If you knew what was good for you, X, you'd want blah!
1v2
Two characters want something from the third character. They may or may not be working together explicitly but they, roughly, want the same thing. Think, good cop, bad cop v suspect
Fewer tags as one speaker on the duo can take the lead, with the other person emoting a lot-- X said, and Y grimaced/nodded/threw a ball at the wall. This can swap around.
Power dynamics are interesting -- leader+follower vs opponent or something else?
1v1v1 / 1v2 and changes to 2v1 / 1v1v1
Starts off one way and revelations cause the nature of the conversation to shift to a different structure.
Power dynamics shift and evolve. The flow is critical.
1v1+1
Two people are having a conversation and third person is talking to someone else and we hear their side of the dialogue. Mamet is the master of this--Glen Gary Glenross has a bunch of scenes where there's a conversation in the office and someone's on the phone. Gives a ping-pong effect to the conversation, creates movement and tension in the scene -- The duo's conversation pauses for reasons and we hear the phone call, which gives us a spoonful of subtext.
3v offscreen
The heist plan. Someone is narrating the goal and the impediments to that goal and the group contributes their thoughts on how they achieve the off-screen thing. Any group narratives are probably good -- Oceans 11, Guardians of the Galaxy, etc,