If your property is sloped, then you have the perfect property for creating raised flower beds. Build your garden bed wall so that it starts low and slowly gains in height as the ground level drops. The end result is that the land changes height, but your flower bed is all one height.
Raised beds also work well when you want a planting bed but can’t plant in the ground. You can have a planter box on legs. This raises the flower box several feet off of the ground. Place the planter box anywhere you want. You can build your raised planter box out of wood. Or you could buy one that’s made of metal, plastic, or composite.