Have tried it with my parents, unfortunately, they eat all this crap from Putin's TV. People who are brainwashed can't really be talked into reason. Politics start and end wars, but a person can break ties with his family irreversible because of those in-family political discussions.
Note that convincing them that they're wrong is less important and much harder to do than convincing them that new things they may see in state media may be wrong. It's about instilling doubt, not about arguing with your parents about politics. The propaganda is most likely going to go into scary territories now, so any doubt will be helpful.
Tell them things that will scare them. Anything that will scare them. How much they will personally come to suffer because of the the sanctions of Russia because of the war in Ukraine. How Russia is not able to import anything. How poor they will become.
