Maximizing annual addition when 401(k) not maximized

If for 2025 a participant age 50 made 401(k) deferrals of $7,500 can they make a profit sharing contribution of $70,000 (assuming salary supports it) to get to the maximum annual addition by characterizing the $7,500 401(k) deferral as catch-up?

Of course. 

Looking forward to 2026, similar scenario, but the participant is also a Highly Paid Individual for Roth/Catchup rules.  What are the considerations for recharacterizing the deferrals as catchup?  I'm assuming this would require needing to know if the plan is using a "deemed" catchup method and if the participant has not opted out of Roth recharacterization?