To prepare estimates for next year you need to be in your current return. But be careful not to change anything in your actual return.
In TurboTax Online, sign in to your account.
Select Tax Home in the left menu.
Scroll down to Your tax returns & documents.
Select 2021, and then select Add a State (you're not actually adding a state, this just gets you back into your return so you can make changes).
Search by typing in W4. Hit the Enter or Return key to get the Jump to w4 link to show up. Go to the W4 page and it will ask if you want to Change your W4. Click on NO. The next page will start the Estimates.
If you used the download (or CD) version of TurboTax (TT), that is, you currently have TT 2021 on your computer, make a copy of your 2021 return (click file / save as). Name it something like "2022 Preliminary" and then replace your 2021 entries with your 2022 estimates. It won't be exact because the program uses 2021 tables and numbers. But, it should be close enough for most purposes. I use the override feature to change the standard deduction and MAGI numbers, on the forms, where appropriate. This doesn’t work with online TT, because you will override your 2021 return.
The CD/Download TurboTax software also has a What-If Worksheet that you can use in forms mode to quickly and easily estimate your 2022 tax. It lets you copy the figures from your 2021 tax return, make adjustments as needed, and check a box to use 2022 tax rates. The What-If Worksheet does not affect your actual tax return.
You can also try this tool https://turbotax.intuit.com/tax-tools/calculators/taxcaster/?s=1. Enter your regular income first to see the regular tax. Then add the sale to see the effect.
Enter the difference between the sale price and what you paid for it originally as a long term capital gain (LTCG). Enter the depreciation you've taken (if any) over the years (depreciation "recapture") as other income. Depending on how much total income you have LTCG are partially taxed at 0%, 15%, 20% and/or 23.8%. Depreciation recapture is taxed at your marginal rate, but not more than 25% (the Taxcaster tool is not capable of applying the 25% cap).