In plain English
FAR 52.237-1, Site Visit, is a solicitation provision prescribed at FAR 37.110(a), most recently dated Apr 1984. The complete official text is reproduced below, verbatim, from GSA's published FAR source files.
Its text contains no sentence requiring insertion into subcontracts; see the flowdown section below for what that does and does not mean.
Does it flow down to subcontracts?
No flowdown mandate found in the clause text
This is a solicitation provision — it applies to offerors when submitting an offer, not to contract performance, so subcontract flowdown is generally not the operative question for it.
Where it's prescribed
As prescribed in 37.110(a), insert the following provision:
Prescribing reference: FAR 37.110(a).
The official text, verbatim
As prescribed in 37.110(a), insert the following provision:
Site Visit (Apr 1984)
Offerors or quoters are urged and expected to inspect the site where services are to be performed and to satisfy themselves regarding all general and local conditions that may affect the cost of contract performance, to the extent that the information is reasonably obtainable. In no event shall failure to inspect the site constitute grounds for a claim after contract award.
(End of provision)