I will write on the Watson deal as if there is no insurance or suspension money removed from it as it makes it clearer and easier to view.
Here is his current contract which contains a dummy year for 2027. This allows the team to Post June 1st cut Watson once the 2027 league year begins in March. This split the dead cap over 2027 and 2028 rather than taking it in one year. The way this guarantees a cut is that if he is on the roster the third or fifth day of the 2027 league year he is guaranteed $200m in 2029, everyone knows he isn't going to earn this $200m, it is there to know the cut is coming.
If they sign him to a one year extension for $6m then it further pushes out the money that would land on the dead cap. This slightly increases the 2027 salary cap but then dramatically reduces the 2028 dead cap. This would move the $200m poison pill back to 2029 for the dummy year in 2028.
You don't make any change like this for the sake of managing the salary cap, you do it because you think Watson can be a $6m player in 2027. I remain skeptical but for me this is his route to staying with the team after the 2026 season.