You absolutely do not need water cooling for a 7800X3D, they can be passively cooled, but a Freezer pro 3. A 420mm version if it will fit. That should see you good for a 24c Ryzen upgrade.
What JRS said. My guess is same as JRS said, your "passively cooled" is normal air cooled case with fans and cpu cooler with fan/s....
Did you mean passively, as in no fans at all? Or did you just mean regular air cooling with a heatsink and fan? 'cause the way the 3D cache is stacked on these chips means that you need some kind of active cooling in my experience.