I recommend using the TurboTax W-4 Calculator since your income has changed and you will not have those big credits for the 2024 tax year. https://turbotax.intuit.com/tax-tools/calculators/w4/ You can also refer to Pub 505 from IRS.gov for more detailed withholding information.
Line 2 of DE-4 for CA will be the worksheet where you can add that additional amount you want taken out.
The number of allowances you claim will determine how much is taken out, so a lower number will result in more income being withheld vs a higher number.
The worksheets are designed to give you a good indication of how much income you will earned and based on that information, the percentage of withholdings is determined. You can use the tables on Pg. 4 of DE-4 to help you calculate the extra amount. This is also the same case with extra withholding on the federal side. There is a table at the end of the form to help you determine any extra withholdings.
