Unfortunately I've not tried that yet but to my knowledge the LCP DD on the Variations isn't too different from the one used on the Moondrop Aria, which I've reviewed and found to have a nice bass response. However it's not even close to Final E5000 in terms of bass texture and such, so I don't think the Variations would perform exceptionally in the bass region vs the likes of Zen etc. let alone the Z1R.
Another thing about the Sony IER-Z1R is the way the drivers are placed inside the housing (check the image below). The housing of the Z1R is exceptionally large due to the inner acoustic cavity where there is a separate resonance chamber behind the DD alongside an acoustic tube that further enhances the sense of "rumble" in the sound (and also makes the decay slightly longer which is unique to the IER-Z1R). If one needs that kind of bass, the other alternative is the Sennheiser IE900 which also uses similar tricks to get a
larger-than-life bass response. Dunu Zen, with its ACIS unit on the back of the IEM, also does something similar.
Moondrop variations and other psuedo-custom shell IEMs don't have such sophisticated structure to enhance bass (I haven't seen one yet). It's mostly the venting mechanism and the length/diameter of the tube that they change to increase/decrease bass and thus falls behind the "bass specialists", I'd say. Simply adopting a stiffer diaphragm material with high excursion won't work.