The M2210 will automatically be created when needed.  Follow these steps:

1. Log into return
2. Return to state section
3. Select Mass
4. Continue through to You've Finished Your Mass Return
5. Scroll to the bottom option, Your Bottom Line
6. Update/ Start/ Edit

or How do I preview my TurboTax Online return before filing?

Perhaps I should have asked "How do I modify the M-2210 form TurboTax creates for me so that I can fill out Part 4, which would allow me to reduce the penalty by reporting that my income was not received evenly throughout the year."

To get to the Massachusetts Estimated Taxes you will have to go all the way through the state tax interview.

You will finally come to "Do You Want to Pay Massachusetts Estimated Taxes for 2021?" Respond yes.

The next page asks "Farmer or Fisherman?"

Respond No.

Finally you'll get to the "Estimated Tax Worksheet."

You can make your modifications here.

I cannot get to the Estimated Tax Worksheet using the instructions here.  I am using TurboTax Deluxe on my PC, not online.  From the "You've Finished Your Massachusetts Return" I select "Other Situations".  That leads to "Massachusetts Estimated Taxes for 2021" and then "Farmer or Fisherman?".  But after that it asks me about 2021 estimated taxes but never about 2020.  I never see "Estimated Tax Worksheet".

You are correct. For 2020 state estimates, you would need to follow these steps instead:

• Inside TurboTax, in the search box, enter tax payments.
• Select the Jump to link in the search results.
• This brings you to the Deductions & Credits section under estimates and Other Income Taxes Paid.
• Scroll to Estimated Tax Payments and find State estimated taxes for 2020 and click Start.

For more information, see: How do I add Form 2210?

Why is my Form 2210 not calculating lines 18-26 correctly?

Those instructions enable you to enter when you provided estimated tax payments but they do not seem to lead you to a place where you can specify non-uniform income, dividends and interest, and withholdings.  Those items seem to get spread uniformly throughout the year.  For Federal taxes you can spread them non-uniformly and I'd guess the income, dividends, and interest come over to the state taxes but you don't enter the state withholding information when you fil out the Federal form.

If you used the Annualized Income method on your federal return, you will be asked if you want to use annualized income on your MA return.  To do this:

1. Go back into the Massachusetts return.
2. Continue through the screens until you come to Underpayment Penalty.  
3. Click the Yes box to answer the question Do you wish to use annualization method to figure your tax penalty?
4. You will be asked to enter your quarterly income on the next screen.

@corymyers

This does not work.  I never get to Underpayment Penalty.  I poked around at the forms view and think I understand what is happening is I am not being asked about an underpayment penalty because the underpayment amount is below some threshold and there is no underpayment fee.

So, I am good for now.  What I did figure out is there does not seem to be any way to tell TurboTax that my state withholding was not done uniformly.  Data sources tells me that Form M-2210 estimated tax paid numbers include, for each period, 25% of the Tax Payments Worksheet Line 14-Total withheld.  That's not the right thing to do if income and withholding is front-loaded in the year.  I can adjust the information about the timing of withholding for Federal taxes but not for the state taxes.  If I override the numbers in the form version it will not calculate automatically.