If you really want to do it with the online versions of TurboTax, you'll need to create another TurboTax account under a different user ID and start a new tax return, duplicating all of the information from your actual 2022 tax return before adding the Form 1099-R for the 401(k) distribution.
Although it's a bit risky, if you have not yet filed your 2022 tax return with online TurboTax, you could add a Form 1099-R for a distribution from the 401(k) and then delete that form before filing. However, although it's unlikely, it's possible that doing so could introduce some side effect that you would have to explicitly correct after deleting the Form 1099-R.
The CD/download version of TurboTax is much better suited to doing what-if calculations. On the What-If Worksheet available in the CD/download version you can ask TurboTax to use the following year's tax tables. although some cost-of-living-adjusted values may still require manual adjustment. TurboTax's TaxCaster is pretty useless in all but the simplest of situations and usually is not updated for the new year until it is too late to be of any real use.
