I've done alot of things over the course of my training to supplement my mat/ring time.
I'm lifting these days more than I'm rolling, mostly due to the pandemic. I roll, spar and hit mitts twice a week in a garage with a few friends, and lift 4-5 days a week. I was rowing regularly for the year and a half that I was competely absent from live training, doing variable intensity programs.
Now that my back story is caught up, I have always liked lifting as a complement to combat training. I've been doing a Wendler 5x3x1 with a few tweaks to fit my 45 year batterd and used up body, and I like it. It's relatively low volume, but you can ramp it up if you want (or likewise taper it off if you need to). I got the strongest I've ever been in deadlift and overhead press during the pandemic, then hurt my hip and had to recover. Now I'm getting back up to those numbers.
It's supposed to be one major lift per workout, but I tend to do two (i.e. overhead press/squat one session, row/deadlift the next session). I do beach muscle dumbbell exercises to finish the session and stretch before hand. The original Wendler is supposed to be a four week program with the fourth week as rest/deload, but I tend to get through it in a week and a half or two weeks the way I do it, including deload.
I'm sure S&C guys would pick apart what I do and they may be right, but the volume and customizeable aspect of the program works for me, and except for the injury I had last year (which is mostly due to a birth defect in my hips), the program works for me because I can keep up with it, and I get stronger.
Also, and I think that this is most important, I like it. I like lifting, so I keep at it. When I was competing a whole bunch, I ran on a treadmill to keep up my cardio and keep my weight down, but without the need to hit a certain weight and know that I can do multiple rounds in tournaments or shows, I don't really care about that these days. I supplement my training mostly for longevity and because I just like to be a strong person, and I feel good on the mats with what I've got going now. Competition and hobby/lifestyle training are different, so it largely depends on what your goals are.
Ok, that's enough rambling.