Every room is different and everyone's taste is different when it comes to audio. What someone suggest that works for them, may not work for you because of this.

For me, the Arc sounds best with the bass at 0 and the treble lowered to -2. My Sub level is 0 and height speakers are at 3, but I do have surrounds and a full size Sub which helps the Arc to immerse you in sound.

You may need a pair os surrounds to get the effect you are looking for. I have the Era 100s which do a fantastic job.

 The Arc alone will not necessarily envelope you in sound from every source.  A Dolby Atmos source will likely do that better than a non Atmos source, but soundbars can’t pull off that surround trick without surround speakers.

 Don’t have a picture of your room so don’t know the best place to put the Sub Mini.  My Sub is to the right of the TV stand and sounds very good.  
 

 Don’t know the crossover point of the Sub Mini, but if it’s anything above 80 I would not want it parked too close to my seated position.  When bass is crossed over at a higher frequency its position becomes more apparent.  Not a good thing if it’s right next to you.

As the Sub is wireless, try plugging it into a long power extension cable and then moving it around your room to find your preferred spot. Once that location is decided, work out how to get the power cable connected.