NOS forks need a service?

Yup, almost certainly. Oil and grease may have dried out/polymerised to some degree. Also worth checking for corrosion inside (but v.unlikely).

Some seals may have cracked too (also v.unlikey if it was properly filled from new!).

Just fitted the 38 Performance elites from Merlin. They are 2022 according to the serial number, and they don't stiffen when lsc and hsc fully closed. Going to whip them apart and refill the damper with new 4wt oil

would they be best sent for a service

I certainly wouldn't send a new fork away just for a oil level check.

Have you done a lowers service or air shaft change before? It's pretty straightforward and good to do it between full services anyway to keep things moving nicely.

I've never taken forks apart, watching a video on a lower leg oil change looks simple enough, will give it a try

I've never taken forks apart, but watching a video looks simple enough...he says

What are NOS fox forks? Google doesn't show anything and not heard of them before.

New Old Stock

Very doubtful that the fork would need a service. Seals will not have dried or cracked as the nitrile rubber has a has a shelf life of 10years at least. The oil in the lowers won't have dried up or mysteriously drained, however for piece of mind you may wish to remove the lowers and replenish the open bath oil, as sometimes the volumes may be a few ml less than specified.