Pursuit for diversity within the US Armed Forces has pretty much eliminated age disqualifications for entry classification (job entry) and assignment actions other than what U.S. Congress has placed in Federal statues. Eligibility is pretty mush determined by Total Force fitness dimensions. General considerations are explained at
Total Force Fitness.
The specific AFSC description in the AFECD and AFOCD gives a bit more specifics. But much of the screening for suitableness to undertake full wartime missions specific to the specialty and perform tasks in various operational environments is why the formal AFSPECWAR Assessment and Selection course exists.
As far as specific age ceilings (cutoffs),
Military age limits for 2021 provides a consolidation of what is in Federal Statutes, DOD policies, and service specific policies.