I would imagine there's a basic "framework" or ballpark discussion well ahead of time, but I honestly wouldn't think Steve is really in the details on these types of things.
Cap management Steve probably cares very little, if at all. The reason he'd be in the loop on deals like this is probably for cash flow purposes. Like if Eric wanted to give Lamar a $100M signing bonus, that's kind of critical for Steve to know that. But we're well past the point where he knows like what the AAV range is, what the range is for total payouts, probably even guaranteed money, etc.
But it is a business, and its a gigantic annual cash outlay. The owner is going to want to know specifics about that and plan accordingly. I think we as fans all caught up in salary cap management and all of that, but none of that is relevant to the IRS or to actual shareholders in the business. Cash flow is what matters, and so a business Owner is likely to care significantly more about how his actual bottom line is impacted than how a fictitious salary cap table is presented. And he obviously is aware of how salary caps can be manipulated and what that entails anyway.
Somebody else asked about Stanley and my guess is the QB contract is probably mostly the one that the Owner would be involved with. Like Stanley's contract is big, but it's not THAT big. Stanley's contract is really just a normal-course-of-business contract every team gives to one of its better players.