Is there anything that could be done to be able to rent more than 25 units?

[byebytoad]

In late game being able to rent only 25 units is quite limiting about what you can do with that.
Is there anything I can do to increase the limit?

 

[Octavius Antony]

Anything that increases your mercenary amount will also allow for more condottieri. Quantity ideas, administrative ideas, aristocratic ideas, and national idea set such as Burgundy's can all increase the amount you can loan out.