These people are your family. Most of them have known you for your entire life. You can disagree (vehemently, even) and still connect on those good family memories. Maybe your older brother has become something of a climate change denier, but he’s also the guy who got you through summer camp as a kid and bought you your first beer in college. Keep in mind the good stuff you share and focus on that.
When you feel tensions rising, a subtle “Hey, anyone want some coffee?” can stop a conversation from escalating. It’s also smart to show up with a few handy distractions—after all, it’s hard to escape the news, so if you don’t try to focus on something else, those hot button issues will inevitably pop up. So instead, come prepared. Give out a compliment or two, “The house looks great,” or pull out your phone, “You guys have to see this hilarious YouTube clip.” And if you’re a games family, bring a new board game with you that’s sure to keep everyone’s mind focused on winning and not on the news.