Is this season 1 update payware? Or free with the base game?
It's a battlepass system.
Maps and new weapons are free.
Battlepass costs 1000 cod points (£10 i think) and as you level it up it gives you free skins and weapon blueprints and other cosmetic stuff.
Battlepass also has free levels where you can earn them without paying for the battlepass. Also you can accumulate free cod points and buy a battlepass that way. I have earned 1100 cod points over the year playing warzone and bout a battlepass. So it was free for me.
No need to pay anything to enjoy the game.