promoting a sim to manager

Hello!

Is there a mod that will allow me to promote one of my employees to management?

I don't think you need a mod for that. It's part of the game, as far as I recall....

Yep, you recall correctly. The sim that needs to be promoted, must first earn five Talent Badge points. A bronze badge is 1 point, a silver badge is 2, and a gold badge is 3. Add the points together for all the badges the employee has, and if the result is 5 or more, the option to promote them to manager appears in the management menu.