I wouldn't use pathfinder or pillars as examples of good turn based combat at all. Those games are built for rtwp and it really shows when you switch modes. Many battles are a slog. I mean legitimate 1 hour slogs and not because of difficulty either. Ambushes, for example, in rtwp you can pause right away, but the same encounter in turn based has your whole party regardless of initiative lose a turn not counting the suprise turn so 2 turns gone.
Encounters need to be designed as a base from the get go for 6 and I don't think it is. Turning up the difficulty does not change design philosophy.
Wasteland is a good turn based combat example because it is designed for 6 man. Xcom as well I think. Its been awhile so I don't remember much about Xcom.
I have no problem with 4 or 6 man parties, but don't act like pathfinder or pillars are good turn based games. Most answers to problems with turn based combat in those games simply tell you to switch to rtwp which in it self a failure full stop. More on pathfinder of course. Pillars is more ai priority than anything and you cant switch in that. Ai simply focus the mc till dead regardless of team existence, position, or class.
If they do 6 man then it must be a base not add on or you will forever fight uphill.