COMPS Analysis - Off market

[PJ Boxel]

I am trying to do a CMA with a property I am intending to buy in St Louis, MO. It is not intended to buy as a flip; however, I need to know the current value to refinance the property and knowing how much to offer. I want to recover most of my capital and therefore buy cash (BRRRR). I suggested that analyzing comps would be a good start, as the appraisers also work this way.

I am stuck in the valuation of a comp. So, for example, how much does the price gets impacted when we compare a 2 bedroom, to a 3 bedroom in the same ZIP? How does this work with the SQFT and age of the property?

This is my current COMP overview, all in the same ZIP AREA, sold <6 months:

How can I determine from here the right valuation and refinancing amount?