Options to reduce reach on a gravel bike
When riding on the hoods reducing the reach of bars is equivalent to using a shorter stem. Only when riding on the tops a shorter stem will lead to different steering compared to shorter reach bars.
A change of 2 cm to 3 cm will change steering. However, it is not so dramatic that you will hit the dirt right away. Especially on gravel bikes that typically have slack steering angles and tend to be quite stable.
Swapping a stem is a bit less work than swapping bars. Stems tend to be slightly cheaper as well. Neither is terribly expensive or much work. You might give it a try and see if you like it.
An alternative would be to lower the height of the bars, by moving the stem further down, and/or flipping it down. When you tilt your upper body at the saddle your shoulders move roughly on a circular path. The lower your upper body is the further your shoulder are forward.
Before starting to get your hex keys you might want too try if you feel to stretched out when you are down in the drops, holding the bars where you can brake.