Ratings tend to drop for most shows from the season/series premiere towards the middle of the season and then get higher towards the end. This is also HBO, they're not one of these trash basic cable networks worried solely about ratings. They let Lindelof get multiple seasons with The Leftovers and that wasn't some ratings juggernaut.
For reference, this season so far is doing vastly better than a show like Insecure did around the same time in its release history, and Insecure is on it's way to season 4. Lindelof will get to make as much or little of this show as he wants.