If it's someone who might not be 100% irredeemable and it's worth trying (like family), I think you have to find a wedge inward that aligns with their values --- or what they claim as their values.
For instance, my mom recently was asking about the whole "defund the police" movement (just asking questions!) Well, what's one thing Repubs hate? Unions! So I explained that police unions dictate police force rules so that even the worst cops have no accountability (accountability!), they get a paid vacation with no consequences, and cities continue to bow to the unions who have a stranglehold over city budgets to allow a shockingly high proportion for an accountability-free PD (fiscal responsibility!) And you know what? Her response was something like, "yeah the unions have too much control..."
Ungrateful thugs kneeling for the anthem? Me: "Yeah I just wish that wasn't one of the freedoms our vets had fought for" with very serious face (freedom!!)
Also, knowing they'd probably voted and would never ever ever consider not voting for every R, I said "hey if you haven't voted yet, please don't vote for this judge (one of my bosses) because he's an activist judge who's a maniac and lacks judicial temperament." I don't think any voter likes to think of themselves as low-info and uninformed, so thought just maybe it'd make her stop and think, and particularly consider how an R could also be an "activist" judge.
My dad has fallen into a very deep state of depression and anxiety and no treatment has helped. I mentioned that watching cable news (obv they are Fox-ites) increases anxiety. I didn't attack the content in any way but told her the format of CONSTANTLY BREAKING NEWS! and the graphics, quick edits, and ever-scrolling chyrons are designed to elicit fear and anxiety. And she told me my dad's psychiatrist told them the same thing.
Speaking of anxiety, she has freely volunteered to me before that "the older you get, the more you hate change." For those with that mindset, it obviously translates into your political views and voting habits. So fearmongering really works. And attacks, even just calmly stating facts, only cement people's views even when they are dead-cold proven wrong, studies show. So my opinion is you have to slip past the reptilian brain response and sneak around the back by using appeals to their own sense of patriotism and values. And it's much more helpful if they don't know that's what you're doing.