To a good approximation, the power absorption capability of the prop of a fixed diameter and rpm is proportional to the total blade area. So doubling the number of blades has about the same effect as doubling the blade chords. But there are a number of secondary effects to consider...

Having lots of blades with narrow chord reduces the blade chord Reynolds numbers. This is bad on models, but nearly irrelevant on a big turboprop.

And if you already have the tooling for a blade and need more power capability, just making a new hub to take more blades is much more attractive than making new tooling for wider blades.

A significant concern is the inertial torque on each blade about the spanwise axis which tries to rotate it to zero pitch. This torque is roughly proportional to the cube of the blade chord, so using lots of narrow blades puts much less stress on the variable-pitch mechanism than using fewer wider blades. I've dealt with wide-blade props where the pitch-change torque was bigger than the propshaft torque at full power! It's good to avoid this.