My steps are how to fill it out in Turbo Tax.
If you do not pay enough tax, you may have to pay a penalty for underpayment of estimated tax. Even if you are getting a refund you can still owe a penalty for not paying in evenly during the year. Generally, most taxpayers will avoid this penalty if they owe less than $1,000 in tax after subtracting their withholdings and credits, or if they paid at least 90% of the tax for the current year, or 100% of the tax shown on the return for the prior year, whichever is smaller. It is included in your tax due or reduces your refund.
I would fill out the 2210 by hand for 2020 to see how it works and if you could have reduced the penalty on 1040 line 38.
