For the benefit of anyone with a similar question:
The ‘status’ values of players/dinos appears to be stored in the ‘Status Component’ this provides a ‘Modify Current Status Value’ method which can mutate torpidity, health, stamina, oxygen, food values etc. It appears to take an amount to change by which can be a value or percentage of maximum/current value or can set the value to that given. (Note it also appears to be able to optionally apply damage at the same time!)
So in BP (and for a dino case):
Pawn -> Cast to PrimalDinoCharacter -> Get Character Status Component -> Modify Current Status Value