Kenku are supposed to have unrivaled abilities for mimicry. This is somewhat represented in Arelith with their bluff and perform skill focuses, but let's be honest, those give a mechanical benefit for Dirty Fighting/Songs/Third Intention only and don't really do anything for RP, since the disguise feature is quite useless for any monstrous race 99.9% of the time.
So why not give Kenku the (limited) ability to switch voice sets? Could limit it to a selection of 5-10 different voices, if it gets too overbearing otherwise.
It provides no meaningful mechanical benefit (so would not be a balance concern), but it would be amazing and fun for RP while highlighting the uniqueness of the race.