I suspect not. The front entrance and the door to Bob & Emily’s bedroom issue from the same wall, in a way that would seem to put the bedroom in conflict with the exterior hallway. Howard’s apartment is directly across the hall yet, in a building that looks homogenous from the exterior, it has a drastically different layout.
Also, the balcony is perpendicular to the hallway entry door, which makes no sense (as I recall, Mary Richards had a similarly skewed apartment in the latter part of the series).
Sometimes it is best to just not think to hard about these things. If you like the show, you just ignore its flaws.
I do not recall any real-world trend toward sunken living rooms in the '70s. Even on TV, there were a few examples, for simplicity in blocking and framing, but it was not all that widespread.
We had one, growing up. House built in 1980ish? But it was a single floor single family home. Seemed pointless with the unnecessary addition of steps where no steps needed.
Split-level houses were quite the thing in the 60s and 70s. At my brother’s house, the front door opens into one level, leading to a living room, and on your right is a short flight of stairs leading down to a “sunken” family room, and just beyond that is a short flight of stairs leading to the second floor.
More to the point of the question, however. While Bob’s apartment may not have been feasible, we once looked at ground-level apartment at a complex that had been built in the 70s, and it had a sunken living room. We were surprised as we had never seen a sunken living room in reality.
The house I grew up in (a two-story, built in 1968) had a sunken living room. It was just one step down from the level of the rest of the first floor, however.
Some good friends of mine live in a split-level, which was built in the early '70s; the living room is on the “main” floor, which also features the kitchen and dining room, but it, too, is sunken by a single step from the rest of that floor.
Or for another example; the apartment building in The Big Bang Theory. Based on the location of the staircase, Penny’s apartment would have to be hanging over the building entrance. And in my experience, most apartments are contained in rectangles that neatly fit in rectangular apartment buildings, but many TV show apartments seem to have bits pushing outside a rectangular box (Frasier’s apartment, for one).
As for sunken living rooms, I think on The Mary Tyler Moore show, Mary Richards’ second apartment had one.
Ann Marie’s apartment D in That Girl (1966–1971) was also split level. We occasionally got an interior view of adjoining apartment C, and the combined layout of the two made no sense. Neither did the arrangement of the exterior brick walls visible through Ann’s living room window.
I would consider a split level to be a completely different thing from a sunken living room. One house I owned once had a sunken living room. There were no steps as it was exactly one step down. I didn’t see much point to it except for aesthetic interest and a slightly higher ceiling in the living room. It was originally carpeted but the sunken effect looked pretty sharp after I installed hardwood flooring.
The OP raises an interesting question about how, architecturally, this could be done in a high-rise building without wasting vertical space. It certainly can be done. In fact my brother’s high-rise condo in New York is single-story but has multiple different levels. I don’t know what the internal construction looks like, though.
Her first apartment was a studio, so the sunken part kind of made sense, and the hallway was just a landing. Her second place was more like a reworking of the Bob Newhart set but with one bedroom and perhaps no outside balcony.
I’m sure the real reason for Seinfeld and Hartley’s layouts was to make the sitcom sightlines better for the cameras, but if an apartment like the Hartley’s were built, I imagine the raised part of the entrance would be matched with a similar one in the floors above and below. Very much like closets in one bedroom can intrude into the floor plan of an adjacent bedroom, and vice-versa. It works well in back-to-back rooms. Or stairways to an attic fit above a stairway to the basement. Or stairways in an apartment building fit above other stairways. No wasted space for either.
I’ve seen single-floor (“ranch style”) houses with a living room one or two steps lower than the surrounding floor. I never understood what was the point of that. Just another step or two for someone to trip over?
I think the vertical space can be varied by varying the height of the crawl-space between floors. This could happen because of the layout of the forced-air ductwork there.
I lived in a house with just one floor level, but the ceiling was lower in the hallway than in the surrounding rooms. That was because the air ducts were up there. I suppose that could happen in a multi-story apartment building too, with maybe the floor instead of ceilings being at different levels.
Most of the places I’ve seen sunken living rooms had an open layout and the different level sort of sets a boundary for the living room and divides it from the dining room or the kitchen , in the same way as the opposite ( raised entry) sets a boundary between the living room and the entry in the apartment in The Odd Couple
