Depending on your filing status, the first $12,550 (single) or $25,100 (married filing jointly) is tax-free, covered by your standard deduction, with a small additional amount if you are 65 or older. (The next $10,000 is taxed at 10%, then it goes to 12% and so on.) Here are the exact figures.
https://www.forbes.com/sites/kellyphillipserb/2020/10/26/irs-releases-2021-tax-rates-standard-deduct...
Don't forget the effects of other income on social security. If your other taxable income plus half your social security is more than $25,000, social security will be partly taxable. However, if you are single and living off savings, chances are you can do a Roth conversion of close to $12,550 and pay no tax. (But don't forget that any taxable interest or dividends will increase your income and count against the standard deduction. Capital gains will not be taxable unless your gain is more than about $38,000.)
If your taxable income is low, it makes excellent sense to do a Roth conversion, at least up to the amount of your standard deduction. You would pay no tax now and no tax ever again. You can likely invest the money in the same instruments, and your IRA custodian should be able to do a direct rollover for you into a Roth IRA with the same custodian (if you like them) or a different custodian.
