I usually rock a barbarian so i just shout or glower for charisma.

But if you’re honestly struggling then i’ll recommend something i used to do to gain confidence. Pretend to be someone else. Like when Abed pretends to be Don Draper. If you act as someone suave then eventually it won’t be an act.

The one caveat is be careful who you’re emulating. Don Draper is smooth but he’s also a giant misogynist. Unless that’s the character you’re playing as, then go nuts.

As a DM, there are two reasons I ask this kind of question.

If it’s a player that I know is comfortable playing their role, then I am trying to get them to lean into the scene to assist with story pacing, or potentially to reveal additional information.

There are still benefits to asking it though, even if a player is not comfortable playing out the scene. Even without a spotlighted stage, you can still obtain a lot of character development by asking for additional clarity. For instance, did the character want to use a cheesy pickup line, or maybe a humorous anecdote, maybe they want to be really suave.

I would probably ask some leading questions like the above, but that additional info can still greatly expand the scene without turning it into a night at the improv.