Hello Angie, currently I use a rental device for pelvic floor exercises by electo-stimulation. A probe with electrodes is inserted into the anus. It should build up the inner sphincter muscles that are important for passive tightness, i.e. when you sleep.
Basically it is similar to conventional pelvic floor exercises, where you are told to imagine pulling out a nail from a board or something like that. But you have a electric stimulation on the one hand and a visual feedback of sphincter pressure on the other which shall help to identify the right muscles.
Sadly I see little success after three months of using that device.