https://www.komoot.com/guide/445/hiking-in-wuerzburg
Here are just some.
There are a ton in the vineyards nearby with trails between Würzburg and Randersacker and nice forest trails throughout Steinbachtal and behind Zellerau/Zell am Main as well. They're about a 20/30 minute walk from the city center. 10-20 minute bus/car ride. If you want to go further the regional trains will drop you off quickly and you can hike back into town. Part of the Camino de Santiago route also runs along the Main River til Ochsenfuhrt. I usually hike twice per week or so and I'm always finding new routes, even if I'm in the same woods.