Depends on how the random value is generated. If you're luckily it uses an existing random function instead of its own. Then you can set a breakpoint at the return function to see where its getting accessed from (might be getting accessed a lOT).
Example for Borderlands 3:
Open disassembly and go to "ucrtbase.rand"
Set breakpoint on the ret instruction (likely better using 'Find out what access' on this)
Ingame trigger the function. If you are looking for loot dropped by enemies then kill an enemy for example.
It is your job then to figure out the actual spot that access these random function and manipulate it this way to always return the same.
A quick way to see if the game uses that function is to write an injection script at the ret instruction and always return a fixed value instead. Then see if your loot for example is always the same or not.
Thank you for the tips, going to load up borderlands 3 and see if I get it right. Current game I was trying to find the random function on uses unity engine, but could never get a breakpoint to go off on the usual functions used for random so guessing it uses a custom version or some other framework that will take a bit of digging to figure out.