Barella only played about 100 minutes in total over the last two matches. He should be fit to start this one. It's Sensi who looked a little off the pace against Milan, though it's hard to be sure whether that was fatigue related or not.
We're about to enter a pretty fucked up run of games so Conte needs to get his rotation right. Too much rotation may spoil our continuity. Not enough rotation may be risky for the players fitness in this congested schedule of big matches. Balance is key. Goes without saying the bulk of the first team should remain the same where it can, though.
For Lazio, the maximum rotation I would consider is Biraghi on the left, one of the forwards, and one of Gagliardini/Vecino for Sensi (depending on how Conte wants to manage the game from the start.)
It's unfortunate that Ranocchia is so incredibly slow and can only play in the center of the 3 CB's. Seems we have 3 options for the RCB role in D'Ambrosio, Godin and Skriniar, but only 2 for the LCB, Skriniar and Bastoni. I really hope Bastoni can get to a point where he can enter the mix as a rotation player soon.