Is the 250kt limit below 10,000 feet MSL varied according to airfield height?
No, the 250 KIAS below 10000 MSL rule of 91.117(a) is not varied within FAA jurisdiction, including near airports with high field elevation.

The 200 KIAS near Class C and D airfields rule of 91.117(b) mitigates some of the risk you might perceive surrounding high elevation airports.

For example, Aspen (KASE) has a surveyed field elevation of 7838 ft and is within Class D airspace. Aircraft operating within 4 NM of Aspen would be speed limited to 200 KIAS up to 2500 AGL, which would equate to over 10000 MSL.

Other high elevation airfields in Class E or G airspace would presumably have less traffic, with the expected result that higher indicated airspeeds would pose less risk in the uncongested airspace..