1. Become an expert in said topic, reading the broad literature, becoming familiar with points and counterpoints, figuring out how research actually works in the field by contributing some papers of your own, and forming your own personal informed opinion on the preponderance of the evidence.
2. Look at the experts' consensus on said topic
Of course, you have other options. A popular one is to adopt the view of one expert in the field that you happen to like, who may or may not accept the consensus view - but this is far more arbitrary than 1 or 2.
So I purpose we strengthen another aspect of American "democracy" that Canadians find amusing, the concept of "hiring people for popularity not competency". Americans, especially at the local level, vote for judges, police chiefs, even dog-catchers, so why not a local scientist! Rather than 1 or 2, we can conjoin this concept with your third option, yet with the officiousness that only a vote can provide!
Each municipality can have a local head scientist, which will proclaim what scientific fact is correct. People can vote on such candidates, and their platform of scientifically correct "things" during election time.
It will all work out very well for them I'm sure, and hopefully, with science thus democratized, perhaps they will be less of a threat over time.
(Sorry, I don't know why your comment made this pop into my head)
https://en.wikipedia.org/wiki/Scientific_consensus
https://skepticalscience.com/explainer-scientific-consensus....
https://tomhopper.me/2011/11/02/scientific-consensus/
And even if you reject consensus as being essential to science, calling the consensus view "the non scientific view" is obviously mistaken, a basic error in logic.
This is all well understood by working scientists so I'm not going to debate it or comment on it further.