There’s an omission in Model Samples documentation: LFO Mode as a destination for velocity modulation.
I’ve not been able to find anything in the manuals to tell you how this works.
There was a guide posted in the M:S Tips and Tricks thread in Mar '20.
However, I have just been experimenting and I think a recent firmware update (1.13?) might have changed things. My update is here
I would really like to see the official docs, as I merely corrected what the previous poster found … there may be more to it.