Most of the integrated RF Power Amplifiers used in mobile phones are two or three stage PAs, using a single transistor in the last stage (with some exceptions in CMOS PAs).
This last stage transistor always operate (more or less) in Class-AB, due to a compromise that is needed between linearity, efficiency, out-of-band noise power, etc.
Even PAs used in Envelope Tracking approach (which theoretically needs a Class-C bias), they bias the last stage transistor slightly in AB class.
And the same, the old standard GSM/GMSK PAs, which theoretically they can use only Class-C stages (due to constant envelope modulation), all of them use the last stage transistor biased in AB class, otherwise they never pass Burst Mask and Spectrum due to Switching test.
In Audio never can use a single stage transistor biased in Class-AB.