It can, but does not necessarily, and does not in every circumstance, increase someone's testosterone.
It's like delivering bricks to a worksite, they could be used for different final products depending on lots of other factors.
It can lead to a new building, but it could also lead to a wall or a well or something else. It depends on many other factors.
Simply taking DHEA and expecting it to boost testosterone is like dropping bricks off on a street corner and expecting a new building. But it is also incorrect to say it does nothing, there could be a work crew with orders to build that are just waiting on bricks to show up.