I wrote an article about some of the spatial challenges involved with office conversion, particularly the postwar buildings that make up most Sun Belt office stock:
https://ggwash.org/view/78585/not-ev...e-apartments-2
TLDR, it's possible but unlikely, mostly because they're too deep. People like to have windows in their bedrooms, but bosses don't like to have too many windows. It's also much more expensive to do so than you think.
Which brings me to the economics: a low-rent office ($20/sq ft/year) brings in about as much money PSF as a high-rent apartment ($2/sq ft/mo), when you balance out things like hallways (apartments have many more) and property taxes (offices pay their own, apartments don't). So the building has to be *really* low-end office to justify the (again, higher than you think) costs of construction.
Pre-war buildings are a lot easier to convert because (a) they're much thinner, having been built before fluorescent lights & forced-air ventilation, and (b) historic tax credits and property tax incentives can substantially offset the cost.