There’s also some legal case law on the subject, because of course there is.

In 1885, the Supreme Court ruled that there were two additional ways in which the United States could acquire federal enclaves: (1) the states could “cede” legislative jurisdiction to the United States, and (2) the United States could “reserve” legislative jurisdiction at the time of statehood. The Supreme Court added that these “cessions” and “reservations” were not limited to Enclave Clause (“needful building”) purposes.[11]

law.cornell.edu