Subwoofers with room correction built in?

@golfnuts - I’ll check out REW, but was hoping to keep it even simpler first…

The only subwoofer that I know of and have experience with that had auto EQ was the Velodyne Digital Drive 12. It worked pretty good. Velodyneacoustics are now located in Germany, but have distributors in the U.S.A. 
That is a true self contained self auto EQ solution which does not require external measuring software or external DSP hardware. It’s all built in and plug and play.  Hmmm, makes me think of exploring the Velodyne subs again. I sold them when we moved due to lack of space and at the time, Velodyne was restructuring and availability in U.S. was non existent. That has changed due to new European ownership. 
Depending on where you are located in the U.S., I located several dealers. 
https://www.velodyneacoustics.com/en/experience/#nordamerika

One thing about auto EQ, unless a separate microphone is included with a long cable reach, Auto EQ will only use the subs built in microphone and EQ the bass for its resting location, not the listening position. Although, it will be better than not doing anything at all, in terms of bass EQ, you made still need to fiddle with the settings if the listening position does not sound right. That’s the thing about integrating subs into any listening  environment, you can adjust by ear, and/or adjust with measurement tools. 
More subs, as others have stated, and scientifically proven, will help to alleviate room anomalies by allowing a flattened low frequency response as long as the multiple subs are not exciting the same room mode, then you have to vary the positions of the subs within the room to help alleviate that issue. At the end of the day, auto EQ should help a lot compared to not doing anything at all, but with the caveats I stated above the measured frequency response at the listening position. 
What are your room measurements? I can send you a room mode calculation which will depict the room modes. It’s not a real live measured response but a scientific approach based on volume and size which normally is pretty accurate. Other factors could play into room modes, furniture, design, construction, etc, but, this approach gives one an “idea” of probable room modes before doing anything. 

Syzygy subs, we’ll built & have EQ, works extremely well. Out of business but still may be able to find. 

Martin-Logan X series can be used with a smartphone app that is OK. Much better results w Perfect Bass Kit.

The smartphone app is good for tweaking phase and level to fully integrate with mains.

In two years, the only negative is they are light and require mass atop them if they are on a compliant floor, i.e. media room above a triple garage with an unsupported ceiling. see http://www.ielogical.com/assets/Audio/SubWeight.jpg - somewhat low WAF factor