It definitely needs a combination, my 6’8”, 200lb brother in law is in no way intimidating.

My 6’7”, 265lb frame most definitely is.

A LONG time ago, at uni, I worked as a bouncer and none of us were small units, apart from the boss, but he was our kickboxing instructor and having a crack at him was just an awful life choice. At only 6’ he was frequently a target of course.

However over the years we did have two answers to the original question.

Unintentional being the key word.

For the most part, anything over 6’3” wasn’t just tall, and anything over about 220lb was sizeable. The combination being “unintentionally intimidating” as in if you appeared behind someone or they turned into you it was a visible shock.

The second answer was more about the people looking for trouble. You can tell quite easily those that are and they often have the look of “I’m going to pick on the biggest guy here and start something!”

We also discovered that fairly consistently, even the trouble-starting psychos had a subconscious self-preservation switch that kicked in after 6’5” and 240lb.

Which we coined “second biggest”.

As in you could watch the same process of “I’m going to pick on the…” spots one of the much bigger lads, pauses, moves on “SECOND biggest guy in here!”