Get a mic and REW and do some measurements in the space.
Are you thinking of the mass loaded membrane traps?
Those are somewhat modellable, but I think you need to have the target freq, and then tune it by adding or taking away a bit of mass at the end… much like a passive radiator.
There are also the round bass traps, which could be added later, as well as active bass “traps”. But starting with the in-wall resonant ones makes a lot of sense.
Once you know the low frequency decay, then just treat the higher freqs so that their delay is similar. (I.e. don’t go overboard with super short ring down times for high frequencies, if the low notes are taking forever to decay.)
The resonant freq on the various places will likely be different along the walls… !
Lowest in corners, then long walls, then short walls.