You don't.
I generally host big family gatherings and I've fully become the "we don't talk politics during family gatherings" guy and I have had to have real conversations with family members about it. My fully MAGA'd sister even managed to alienate me, the last of her siblings who would even bother talking to her (her kids won't even talk to her anymore) because she somehow believes that "no politics at Christmas" is a "free speech" issue. A particularly dumbass in-law (I call him "mouthbreather") has been pulled aside a couple of times, but he's mostly able to contain himself and he generally feels embarrassed after our 1-on-1s.
Early on I asked moutbreather how many sides there were to him as a person, and we agreed there were many. It's simply a matter of putting one side to the background for the evening, and it's not hard.
And it's also a matter of showing your teeth occasionally, so the idiots don't get confused and think your motivation is fear of their bold, unassailable ideas.
We don't have long in this world.