You can use the Turbotax tax estimator, even though it is set up for 2019, you can enter your 2020 information and the results should be similar. Enter your expected income from jobs, self-employment and so on, and how much you plan to withdraw from the 401(k). The estimator will tell you what tax you will owe, and how far short you will be considering your withholding so far. You can have that withheld by the plan trustee or you can make an estimated payment direct to the IRS at www.irs.gov/payments
https://turbotax.intuit.com/tax-tools/calculators/taxcaster/