I believe trim is now available on all default helicopters in MSFS2024. Confusingly there are various flavours of trim commands available. Along with the longitudinal and lateral cyclic trims there are Force Trim and Quick Trim which both accomplish the same type of trim control. That is press and hold the button while returning your control stick to neutral to set this as the new neutral. For the H125 you should use Quick Trim to accomplish this. Force Trim doesn’t work on this one. Quick Trim has worked on all helicopters I’ve tried it on so far so that’s the one I am now using by default.