Don't support bridge is a good idea to reduce support with acceptable print quality. But in this case, if I have a very long bridge and a short bridge, how do I tell the slicer to generate support only for the long bridge. How can I set some parameter like bridge length threshold?
Regardless of the choice of long bridge support or short bridge support, Prusa Slicer 2.3.0 has a feature which allows forced support or allows forced no support.
In Advanced or Expert mode, there is an icon in the left tool bar for "paint-on" supports. The left mouse button paints on supports, while the right mouse button creates support blockers. Shift-left mouse button erases errant paint splatters.
There are more details in the linked video. It's not a parameter, but it is a means to determine where you want (or don't want) the supports.
According to a thread in the Prusa support forum, in order to have the enforcer and blockers operate as expected, configuration settings should be for supports off. This may have changed as the thread is older and may have been modified in newer releases.