This question already has an answer here:
I believe there is a term for a person who uses 'expert sounding' terminology and exudes confidence, even when their actual abilities are significantly short of their 'presentation'.
Using 'wine' a subject.... if a person described a taste as:
Magnificent bouquet, the esters resonate with hints of mulberry and asparagus. This must be an oak-matured red from Bordeaux. Perhaps.... 2003 vintage, that was a year when unusual rainfall produced an outstanding crop that had the same rich tannins.
A person describing the wine like that has apparent confidence, apparent technical expertise, and so on. Yet, if he was a fraud, and knew nothing about wines, and the "wine" was really vinegar.... what would you call that person? Additionally, this would not be a one-off thing. This would be a person who consistently "bamboozles" people, and only when you dig below the posturing, or put them in the company of a 'real' expert, do you see the reality.
A fraud, a cheat, an imposter. Those would be true, but I'm sure there's a word which also covers the confidence, charisma, and presentation style too.
I just can't think of it.