CBE, ASC, BSC
looks good for your intended look. I like all the small battery powered lights available these days in replace or set near practicals as they are controllable for color temps and output and no risk of flickering etc. so basically lighting with practical positioning but using better lights/ bulbs etc. if that makes sense.
Honestly I’d keep using the S5 id you already own it. I just bought one myself. Better sensor and low light performance than the BM cameras IMO and I find Panasonics V-Log and color science one of the better LOG profiles. The IBIS in the S5 is great. I hate to say it but if you can’t get the images you want from the S5 the other cameras are going to be any better, Id invest in lenses or if you are wanting better recording codecs an external recorder like the BM Video Assist or Ninja V. IM not sure there is a better camera under $2k.
While its not FF the Panasonic GH6 has open gate 5.8k.
I agree with Al. Zooms all the way for doc work unless you are just shooting talking head interviews and some b roll you could get away with primes but if you are running and gunning nothing more convenient than a nice zoom that’s wide to medium tele.