"All of these copilots are supposed to make work more efficient with fewer people, but my business leaders are also saying they can't reduce head count yet."

Duh, if they reduce headcount then they will have fewer people in their department, which will negatively affect their chances for promotion and desirability of their resume. That's why they actually offshore the jobs to India and Southeast Asia; it lets them have 3x+ the headcount for the same budget.

If you want to have them actually reduce headcount, make org size the denominator in their performance reviews, so a director with 150 people needs to be 15x more productive than a manager with 10, who needs to be 10x more productive than the engineer IC. I guarantee that you will see companies collapse from ~150,000 employees to ~150, and profit/employee numbers in the millions (and very likely, 90% unemployment and social revolution). This is an incentive issue, not a productivity issue. Most employees and their employers are woefully unproductive because of Parkinson's Law.

You'll never see a manager or even a managing-CEO propose this, though, because it'll destroy their own marketability in the management job market. Only an owner-CEO would do it - which some have, eg. Valve, Nintendo, Renaissance Technologies. But by definition, these are minority employers that are hard to get into, because their business model is to employ only a few hundred people and pay them each millions of dollars.