The Denon is a very capable unit that supports multiple surround modes. As others have mentioned, you have a LOT of setup options available, and budget will be a major player in what you can accomplish.
It would be helpful if you could upload a drawing of your room (doesn't have to be all that good) with some measurements. That way you can receive better direction on what is avaiable.
Likewise, your location, in case you aren't in the USA.
Also, any desires you may have for the speakers. There are a TON of models, but basically, they break down into floorstanding, bookshelf, on-wall designs, and in-wall designs. It's important to remember that really small speakers simply don't have as much oomph as larger speakers. But, in a family room where you may really want no intrusion into the space, you may want some decent in-walls. In a basement rec room, some towers may be a great choice.
Finally, depending on budget, it may make sense to just get a couple of speakers (stereo) and then add a subwoofer, and more speakers over time as budget allows. This can get you going with good sound.
As mentioned, go from your sources (Blu-ray, Streaming Device, Cable Box, Game Console) directly into your AV receiver. The receiver will peel off the audio and send it to the speakers you have connected, and will pass the 4K video right on to your display.