Also make sure you understand when the 10 years ends. For example, if your relative died this year, does 2020 count as year 1? (I think it doesn't, but not sure.) Does year 10 end on relatives date of death or end of that tax year? (I think end of tax year, but that's just a logical guess.)
The 10 year period ends at the end of the calendar year that contains the 10 year anniversary of death.
So if the relative died today, then 10 years from today is September 8, 2030, and so you would have until December 31, 2030 to empty the IRA.
If the relative dies early in the tax year and the beneficiary can effect the transfer into their name early enough, the above means you can actually sometimes have 11 tax years to play with. In the above example, 2020, 21, 22, 23, 24, 25, 26, 27, 28, 29, 2030 is 11 tax years.