The variation on Ronaldo's play is overstated. RM's squads have renewed greatly over the years and they've had different formations but the plays where Ronaldo scores have by and large been a result of heavy buildup on the wings and a huge emphasis on crosses/1 touch finishes and 1-2 man fastbreaks. As I said before, especially under Zidane, it's become a routine of 2 variations of a crossing play once they get to the final third and very little else. It's not like Ronaldo has been out there taking down parked buses with his dribbling and then scoring, or longshots and scoring (not for the past 5 years anyway) and doing different things against different opponents or situations. His scoring is pretty consistently uniform and the actual situations where he's involved have remained the same, despite whatever formation/roster changes he's dealt with.
Also, you said that he did it with a midfield of Kovacic/Casemiro/etc. But in that game, RM actually did STILL manhandle PSG's midfield. They had more possession, produced almost 3x as many shots (only 4 to Ronaldo, so they weren't just creating because of Ronaldo's runs or whatever which is a totally fictional narrative), more than 3x as many key passes, etc. As well as the fact that Verratti only played 2/3 of that game before getting sent off and both of RM's goals came AFTER the red. Casemiro also had an insane game, he truly is one of the best DM's in the world right now. It's not just about the midfielders but the fullbacks in Marcelo/Carvajal as well who are crucial in progressing the ball and creating chances for them.
In reality, RM have not been on the losing side of a midfield battle in the CL for a while now. In fact the only opponent that has really ever outplayed them there since Zidane took over was Tottenham this season in the 3-1, where Ronaldo's goal came from a stupid error/rebound.
And in these past 2 years and even before that, RM's definition of losing a midfield battle has been different from Barca's. They can get outplayed, but still make quick transition plays on the other end and create a lot of chances. They still find space a lot and generally do go back and forth with the opposition midfield. For Barca it's getting thoroughly outrun/outpressed in midfield while lacking a forward outlet in Rakitic, or playing ponderously slow against a parked bus and not penetrating whatsoever. In these cases they have an insanely difficult time even getting the ball past Busquets/Raki/Iniesta who are all forced to play a lot deeper. Whereas in RM's midfield upsets they are still going end to end albeit less effectively than the opposition. Part of this is that they have the better personnel to deal with adversity in midfield and also that Barca's style can stalemate them in some games because of how specifically they play.
A game where RM are being properly outplayed in midfield the way Barca have been usually goes with a 'Ronaldo was completely invisible' performance. Like many Clasicos in the Pep days, the 0-4 Clasico at the Bernabeu, Dortmund in 2013, vs teams like Germany/Spain/Chile with Portugal, etc.
