As I said in the WandaVision thread, I believe that this is generally true, but there are big exceptions to this standard. To me, the Flash is more relatable than Doctor Strange, Batman is more relatable than Falcon, and Wonder Woman is a better made character than Captain Marvel (going by the movies). Besides those glaring outliers of this rule, I think this is mostly true.
Spider-Man has more real-life problems than Superman. Superman's "real life problems" are so non-existent that the only disguise he needs to hide his identity are a pair of glasses. The most relatable thing about Superman are his relationship problems, but even those seem to be easily solved and less relatable than those that Spider-Man has, who has to balance work, school, and a girlfriend with his crime-fighting.
Iron Man's origin story is more relatable than Batman's. Though they were both able to get their "powers" from being born into incredibly wealthy families that met an untimely end early in the heroes' lives, Iron Man's origin of being able to escape from terrorists with the help of a mentor using their natural skills in order to help the world just feels more drawing than that of Batman's, where he just decided to fight crime because he still hadn't gotten over his parents' deaths and fear of bats.
The X-Men are discriminated against because of their powers that they received at birth, which is very relatable to a ton of people that suffer discrimination in the modern world. This is just hands-down more compelling of a story than that of Aquaman (IMO, of course). Though Aquaman is Half-Atlantean, Half-Human which has caused him to face discrimination from both Humans and Atlanteans, he easily overcomes this and is able to become the King of Atlantis and get "everyone" to love him. The most compelling part of the X-Men is a better plot point because it is not easily resolved, and both sides have good points. Mutants are dangerous and can cause huge catastrophically disastrous events that have the potential to destroy the world, but they didn't choose to be born that way and should not be discriminated against because of how they were born.
These are just a few examples to support my point, but I could bring up others if I needed to. On the scale of "Epic-ness" and
"Relatable-ness", I feel that Marvel heroes generally leans more towards being relatable while DC heroes lean more towards being epic. (That is not to say that these are incompatible characteristics. There are indeed very "epic" characters that are also very relatable, like Wanda, Wonder Woman, Iron Man, Post-Ragnarok Thor, the Flash, and others.)
So, I guess my answer is "Sometimes no, but usually yes".