I have found arguing with people does not work - their beliefs are so tied with their being that if they let them go they destroy themselves.
Now some beliefs are relatively harmless - like if you are a Patriots fan or believe Ford makes the best trucks, but some are dangerous, like Democrats are going to take away my guns, or that our elections are rigged.
Now I am working on some ideas of my own - egotistical? Maybe.
Some things we can do:
1. Expand fact challenging (not fact checking) Ask people to show you the facts rather than telling them what you think the facts are.
2. Treat conspiracy theory spreaders like criminals - have a nation wide social media ban - like a no fly list for serial offenders - they are really no different than terrorists of the mind. This will require a BIG change to how we look at free speech - i.e. you have the right to free speech but I do not have to be an amplifier for you. Twitter and Facebook are moving in this direction. Of course if they move to a subscription based service, that eliminates any argument against it. Of course doing away with anonymity will help. Getting rid of comment sections on news sites will also go a long way to more civil discussion.
3. Or ditch social media all together - I stopped watching nightly cable shows a long time ago and an enjoying my evenings. I snooze Facebook friends at the slightest political (not philosophical) post.
4. Teach our children to think - easy with some - tougher for others. The funny thing is that for the most part - the younger you are, the less you fall for fake news, but as you get older, even kids who grow up with technology start to fall back - so it may be a psychological not an intellectual issue.
5. Stop reading what Google and Facebook send you - start reading about what interests you. By searching out knowledge for knowledge sake - you will wean yourself of the garbage that is force fed to you.
Of course I must be an optimist to believe any of this can come true.
As Pliny the Elder said (probably not Nelson Mandela) "It always seems impossible until it is Done".