You can open your 2019 tax return and go to the section where you can prepare estimated taxes for next year. Type estimated taxes for next year in the search box and click on jump to estimated taxes for next year in the drop down box. Say no to the first screen where it asks if you want to change your W-4 and continue on.
You can also use the TaxCaster tool for estimating taxes: https://turbotax.intuit.com/tax-tools/
