I think you're right on Parsons getting a deal done, however the Cowboys have already picked up that option year and he is currently counting $21M against the cap for 2025. If they work out a deal so he only counts $15M against the 2025 cap, they free up $6m from the current projections.Plus you have to factor in that even if a new deal is reached that 5th year option doesn't just go away. Justin Herberts contract from this year is a good example. He signed a 5/$262M contract however it's really a 7 year/$300M contract he has because he will still be playing under the last year of his rookie deal in 2023, 5th year option that was picked up in 2024, and then his new extension starts in 2025. With his new deal it allowed LA to lower his 2024 cap hit from $29M to $19M by shoving some of that cash into the back end of the deal.
Similar with Dak....he has $40M in void money being counted towards next years cap already. An extension for him lets the Cowboys move that money around. Depending on the structure of that deal he may end up counting less than the $40M in 2025 that is already being factored in.