Is the first row of buttons on a double breasted jacket functional

Elements of a Bespoke Suit: The Cut, The Single or Double Breasted

Black double-breasted blazer with gold buttons

Can a waistcoat, preferably with a lapel, be worn in a cotillion without a jacket? - Quora

Why do some men (even some in senior business positions) wear button-down shirts with 3+ buttons undone, so you can see a bunch of their chest hair? - Quora

How many buttons should a waistcoat have in the UK? - Quora

Suit Jacket Button Closure Rules You Should Know

What button should I close when wearing a three buttoned jacket? - Quora

Is it more important to wear a vest under your jacket or to unbutton your jacket when wearing a two or three piece suit? - Quora

The Four-Button Double-Breasted Jacket Is Back—Here's How to Wear It

Elements of a Bespoke Suit: The Cut, The Single or Double Breasted

Why is there an extra button on coat sleeves? - Quora

How should you button your suit jacket lapels over your shirt collar correctly? - Quora

How is buttoning effective in a suit jacket? - Quora

The rules and how to break them 8: Button a DB – Permanent Style

Single Breasted Suits vs. Double Breasted Suits 101 - Oliver Wicks