Space Marine 2 lead says Doom 2016 was a big inspiration, just as the original Doom inspired Space Marine 1 which in turn inspired Doom 2016: "It's a grand circle of coolness"

gamesradar.com:

Warhammer 40,000: Space Marine 2 is nearly here, 13 years and one massive leak later. According to chief creative officer Tim Willits of developer Saber Interactive, previously studio director at Doom house id Software, the upcoming sequel was looking directly at the modern Doom for reference on some key details, and he reckons the two series have traded notes multiple times over the years.

Speaking with GamesRadar+ at Gamescom, Willits argues "one of the things that a lot of gamers, I believe, do not understand is how influential Warhammer 40,000 was for so many games. The original Doom marine looked a lot like a Space Marine. The chain sword in Gears of War was not the first chain sword. Even the power armor in Fallout, it looks a lot like a Space Marine." 

This comes to an especially sharp point with Doom and the Space Marine Warhammer games. "I know nothing about the original team at Relic that worked on the original [Space Marine], but I believe that they were inspired by, obviously, Doom and Quake," Willits says. "But what I do know is that when we were working on Doom 2016, we looked at the 'push forward' combat that they did so well in the original Space Marine. And we leaned into that push forward combat that Doom 2016 is a signature for. And then in Doom, we added the Glory Kills, and the Space Marine 2 team looked at that and was like, 'That's awesome, we need more of that.' So you can see these over-the-top Glory Kills that are in Space Marine 2 - obviously, you know where those were inspired from.

"There are lots of similarities. For me to work with the team on a Space Marine game after working on so many games that have pulled inspiration from Space Marine is a great honor for me. It's a grand circle of coolness," Willits concludes. 

One element Space Marine 2 has heavily emphasized is the sheer power that Space Marines command. It deliberately caps co-op at three players because you're already "almost invincible," so adding any more Space Marines