You can only set the RNP for which the aircraft is certified, Airbus is not certified < 0.3, Boeing much less, in fact Air Alaska is the first airline in the world which had designed, and certified RNP approaches in JUNEAU Airport, it is worth doing some research.
The Air New Zealand Airbus A320 is certified for at least RNP 0.3. Air New Zealand is operating the A320 into and out of Queenstown on RNP AR approaches. Air NZ has had a lot of work done with Airbus to move toward PBN approaches.
Jetstar are using the A320 with whats is known as RNP lite using 0.3 at Brisbane.
The Air NZ B737-300 and Qantas B737-800 have been operating RNP AR into Queenstown for three years. Air NZ are using 0.3 and Qantas are using 0.15 both are planning 0.11 approaches.