If you make large charitable donations, the deduction covers the under-withholding. It's a non issue.

You can (and are "obligated" to, or face (tiny) penalties) make quarterly estimated payments, if your withholding is too low, if your total Federal income tax owed is over 10% higher than last year.

Every vest- review your stock statement and check how much tax got withheld. Then cover the difference to get to a 35% rate- either sell more stock, pay cash, etc. It’s annoying but not very hard. You have the money.