There have been one or two past questions on different variations of "blowhard," but no answer quite gets at an emblematic recent incident. A famous senator attributed the quote "all sound and fury, signifying nothing" to Shakespeare and a famous journalist "corrected" him and told him, "no, that's Faulker." So, eager to one-up someone based on ignorance and laziness (i.e., couldn't be bothered to google the quote). "Ignorant blowhard" doesn't quite capture the implied feverish desire to put one over on someone without really knowing what you're talking about. Other words?
The phrase feels a little dated to me, although ngram shows it to have interested tenfold since about 1990, but I like:
Pompous Ass = A person who seems full of themselves and who grabs every opportunity to let others know of their feelings of superiority.
noun: someone who is always trying to seem more clever than anyone else in a way that is annoying.
adjective: always trying to seem more clever than anyone else in a way that is annoying.
source - Cambridge Dictionary