Your 401(k) withdrawals will automatically withhold 20% for federal taxes unless you provide the plan administrator a Form W-4P to change the amount of taxes being withheld.
For your IRA you should provide that plan administrator a W-4P indicating the amount you wish to have withheld when there is a withdrawal.
If done correctly there would be no need for you to pay estimated taxes.
IRS website for a Form W-4P - https://www.irs.gov/forms-pubs/about-form-w-4-p
You can use the TurboTax calculator TaxCaster to get an estimate of the taxes owed for the withdrawals - https://turbotax.intuit.com/tax-tools/calculators/taxcaster/
