Answer:
There are many ways :)
Step-by-step explanation:
If you mean by research purposes and trying to find if the source you're looking at has the correct information, sites like .gov, .org, and official news articles are your best bets :)
But if you mean if a source is popular or relevant enough in that sense then the best way to figure that out is to ask around or see how many downloads or visits it has. You can also do a little bit of research about how/if/why this site or app is popular. Hoped this helped :)