https://www.theringer.com/mlb/2021/3...review-two-way
Article above written in March 2021, before the start of Ohtani's 4-year reign of terror, but after his struggles in 2020. Sounds like he and the Angels put a lot of thought into his regimen. Interestingly, they took away restrictions on his workload, allowing him to actually do more two-way stuff rather than less.
He also started squatting heavy again and came in at 225 pounds in spring training in 2021. I'd imagine that helped a lot, especially after his 2019 knee surgery.
As an aside, Ohtani is still listed right now at 210 lbs, but he looks like he's a lot bigger than that when you see him standing next to Bryce Harper -- who's also listed at 210:
https://x.com/MLB/status/1811061670493511797/photo/1