Depends on what type of ride you are looking for. Road rides are discoverable on Strava Heatmaps - the brighter the line the more people who ride that route.
If looking for off-road or gravel rides, I use Google Earth/ Maps satellite view - look for gaps in the trees that can indicate a road or cut that is not officially a road. If you have access to old topo maps they can be an excellent resource, too - compare old map to new map and you are likely to find roads that used to be marked are no longer included on maps, but are likely still there and passable.
Powerline cuts are also often excellent rides and often have many trails going off in every direction if you keep your eyes open.
If exploring off road, be ready to turn around if you find a dead end, or to sheepishly apologize if you find yourself in someone's back yard and they are out mowing their lawn. The vast majority of people don't seem to mind when this happens to me, and I usually wind up skirting their fenceline towards the road to escape.