Until you address room acoustics, nothing you do will matter much to improve your sound quality. Given your room dimensions, the critical distance, the point at which the reverberant sound level equals the direct sound level is between 18 and 24" in front of your speakers. At a normal listening distance, about 90% of what you hear is the room. Room equalization, contrary to popular belief, can do nothing to address this, as it only affects the input INTO the room and not the reflected OUTPUT, the reverberant field, of the room.
Some recommendations have been made using rugs and furniture - they will help a little, but a small room treatment package, including 6 - 2’X4’ 2" custom covered rock wool or fiber glass panels and a couple bass traps is really the answer. Room calculation will show you the recommend minimum square footage of coverage for your room. Acoustimac https://www.acoustimac.com/room-package-deals/home-theater-packages makes a great package for about $850, covered in your choice of materials and colors that will do the job. Once hung wall panels are easy, youll need a friend and a stepladder for the ceiling), you will hear a found improvement, and can start with other tweaks like speaker placement and toe-in which will now be easily audible. And don’t believe that more expensive panels work better. Under the covers they’re almost all Fiberglass 704 or Rockwool.