One of the biggest ways delusions keep a hold of people is by disconnecting them from supportive / positive social relationships. The deeper down the rabbit hole they go, the more people they argue with, and the less non-delusional friends they have. Try to figure out what those beliefs and social groups replaced, then get them back into supportive social groups around that. Often it’s a hobby like gardening, book clubs, cars, sports, hiking, etc.
That’s why all of this took off so hard during COVID, people got ripped away through all of those things and Russian disinformation bots were right there and ready to replace that sense of connection with a sense of being part of a larger movement. Sometimes it’s spiritual or religious groups which has been difficult because so many of those groups have just become completely overtaken and become vehicles for the delusions, so we also need to work on ways for people to express their religion and spirituality in non-delusional ways, but that’s a whole other discussion.
The short version is: make the delusional stuff subtly less accessible (encourage them to get away from the computer and TV) and try to get them into other positive activities that connect them with other people and help them move their focus away from the delusions without directly confronting them.