Here is what the Cubs saved by delaying Bryant's service clock (*projecting his last 3 arb years):
2015 (age 23): $0.550M
2016 (age 24): $0.650M
2017 (age 25): $1M
2018 (age 26): $11M
2019 (age 27): $16M*
2020 (age 28): $21M*
2021 (age 29): $26M*
They gained his age 29 season for $26M, which would have cost them upwards of $40M if he were to become a FA.
Acuna could very well top those numbers. If he does, the season in question (2024) will be his age 26 season. The Braves can control that age 26 season for $25M-$30M, or they can let him hit the FA market and likely command $50M per year in a mega FA contract.
It is imperative the Braves control at least his age 26 season, even if they have to raise a stink similar to what the Cubs did with Bryant. We've gone over giving Acuna a record setting deal (beating DeJong's 6/26 +2 options) once he completes this season, and we've gone over the Singleton deal for $10M before he even steps foot in a real MLB game.
What kind of extension would it take for the Braves to allow him to be on the team opening day? It would be completely precedent setting.