No it isn't.
It's not a criminal offense, but if someone can sue you for it and win then it isn't "legal" under any technical or popular definition of the word.
Otherwise, less any examples of enforcement or successful legal action, downloading movies is illegal in the US in the same way that blasphemy is illegal in Michigan.
https://www.legislature.mi.gov/Laws/MCL?objectName=MCL-750-1...
It could be argued that if you bought a movie, say on DVD, downloading another copy of it from an online source could fall under fair use, but this is more debatable.
[0] https://legalclarity.org/is-pirating-movies-illegal-what-are...
Even the Protecting Lawful Streaming Act of 2020 explicitly does not punish consumers of copyrighted content, only its distributors.
>Tillis stated that the bill is tailored to specifically target the websites themselves, and not "those who may use the sites nor those individuals who access pirated streams or unwittingly stream unauthorized copies of copyrighted works"
There are so many paragraphs in response to my “You can’t get in trouble for downloading movies in the US” post and none of them have any examples of people getting in trouble for downloading movies in the US.