Do you really think you could get a Ph.D. in three years post baccalaureate? I doubt you could at a reputable school.
For a Ph.D. you need to have two foreign languages, take and pass comp exams, pass your dissertation proposal and write and defend your dissertation. Oh and you’ll probably need computer/analytical skills. Some people need two years just to get a masters degree.
It may not be extremely common but my brother did, in Physics at Yale / Yeshiva. Most all of the doctoral candidates had already picked up German but I don’t believe there was a formal language requirement. Many knew some Latin, as well.
I dropped out in the third year just before submitting a dissertation proposal. There definitely was no foreign language requirement.