It's not the 1950's anymore. In any job where workers have a modicum of bargaining power, it's perfectly fine. This goes treble for tech, which skews younger, less conservative and suffers from severe labor scarcity.
Tech? Please don't make me laugh. Working at MSFT for a while, I've seen plenty of people in-person (even in management) with visible massive tattoos (even one with full neck covered in ink), piercings, and I am not gonna even start on wild hair styles and colors. One of the very senior people I've gotten a chance to work with had her hair color being split in half right down the middle - half black half white (ala Cruella from Disney's 101 Dalmatians). And mind you, out of all the big tech companies, MSFT is one of those that imo skews a bit of an older crowd, so I don't doubt this kind of stuff is even more common at places like FB.
One of my friends is a doctor in the deep south, and his arm is fully tattoed and is on open display at work (short sleeves). From my anecdotal experience, every time I go for an annual physical checkup with my primary doctor (in PNW), more than half of his nurse staff has either bright-colored hair or tons of tattoos (or, not uncommonly, both).
All of this is extremely acceptable in the US these days, barring few specific industries that still insist on ultrastrict "suit-and-tie" dress code and some rural areas. But in major cities? It would be impossible for me to walk through a block on the street without seeing at least one person with either neon-colored hair or very covered in ink or with tons of piercings.