Quake Champions Executive Director Tim Willits tells Polygon that "at its core [Quake Champions] will be free"

Players who want to can play Ranger for free, or they can buy the Champion Pack and get unlimited access to Ranger and all other champions for a fixed price.
At its core, it’s a free-to-play game,” Willits said, “with the option to buy the Champion Pack and just get in and play with all the Champions. There are a number of Quake players that just want to play their Quake, right? And they are familiar with the business model of our previous games, and they are totally fine. ‘I want to buy the game. I want to start playing. I want to have access to all the Champions.’

“But then we also understand that we want to get as many people into the game as possible, especially outside of North America and Western Europe, where we have a massive fan base. So we want to have the flexibility to have a free-to-play option for those people.”

“We do feel it's more approachable,” Willits said, “and we feel that with our team game modes, and then especially our dual mode, that we can fill a hole that's missing in esports today.

“We do have a really nice advantage, because lots and lots of the pro players got their start playing Quake. And yeah, they're playing Counter-Strike: Global Offensive now and, Overwatch, but their first love is Quake. So we want to get that critical mass where you have enough players and then we want to ... expand our competitive play, our league play as we move into late this year and next year.
Source: polygon Interview