Sonny Gray would be a fantastic addition to the Braves rotation
If the Braves were wanting to go a bit bigger and/or really heavily invest in their rotation, the best option available this offseason outside of Ohtani for the Braves is probably Sonny Gray. Sure, Aaron Nola is going to be a free agent, but it sure seems like both the Phillies and Nola have a decent amount of interest in staying together plus he will likely be out of the Braves' price range anyways.
In Gray, you get another guy that just puts up low to mid 3 ERAs every single season. Right now he is amidst one of the best seasons of his career which could drive his price up, but he is also 34 years old and doesn't have overpowering stuff. With a decent amount of money coming off the books (especially if they don't pick up Morton's option), the Braves could afford to give Gray a three or so year deal and really shore up their rotation assuming, of course, that Gray doesn't end up retiring.
Keynan Middleton would give the Braves even more bullpen depth
It is a mortal lock that the Braves' front office will sign at least one reliever this offseason. You can chisel that in stone. While some of the Braves' guys who are set to hit free agency could end up signing back with the team, one name to keep an eye on from outside the organization is Keynan Middleton.
On the surface, a bullpen arm with nearly a 4 ERA isn't particularly exciting, but Middleton requires a closer examination. The vast majority of his peripherals look really strong and his Statcast profile has a whole lot of red on it (that's good). Additionally, he isn't considered to be a lock-down closer type on the market so signing him shouldn't be too cost-prohibitive. The Braves love upside in their relievers and Middleton could be a nice pick-up towards that end.