Have to use 2 inch pipe for exhaust is it better to use 4 inch inline fan or 6?

Hey so I have a nice little grow room that I built the only problem is my only air exhaust option is a 2 inch pipe originally used for the bathroom fan since I live in a condo. I previously had a 4 inch inline fan runing through 4 to 2 inch reducer. Then switched to 6 inch inline fan connected to a 6 to 4 inch reducer and another 4 to 2 inch reducer. While they are both far from my ideal setup my question is which would be better. Below is a pic of the 4 to 2 inch adapter on 2 inch pipe and current 6 inch fan setup with 6 to 4 inch reducer taped on end. The 4 inch fan is currently being used as intake fan. As of right now I’m leaning towards leaving it as is but wording the double reducers are doing more harm then good let me know if anyone feel opposed and really explain why.

Also the space is 5.1ft x 5.6 ft = 28.56 Sq ft

The 6 to 4 inch isn't an issue. 4 inch can flow roughly 4 times more than 2 inch and 6 inch can flow twice as much as 4 inch.

some basic rules if trying to maximize velocity
-The longer and more gradual the reducer the better.
-keeping a straight run at least for the first 3 feet off the fan before making any turns
-Sheet metal will give you more velocity than flexible duct but will be louder
- running the duct and reducing as late as possible in the run will help so you would wanna run 6 up to the attic and reduce at the exhaust

The clever move might be seeing if it is damaged, then see if the condo association will upgrade it. then you'd at least have a 4" outlet so it wouldn't be so restrictive. They are responsible for the roof so it would be on them if there was damage to the boot going through the roof not the pipe itself

Are you sure that's two inch?

The 6-4 inch looks as it should.
The 4-2 looks more like 4-3 inch