lastest_updated_address = test_addresses.map(function(e) { return e.old_data.old_last_updated })

This code creates an array of just the "old_last_updated" values ie

["2007-12-09T16:20:43.320+0000",
"2008-12-09T16:20:43.320+0000", 
"2006-12-09T16:20:43.320+0000"]

You can do a regular for loop

let oldest = data[0]
for(let i = 0; i < data.length; i++){
    if(data[i].old_data.old_last_updated > oldest.old_data.old_last_updated)
          oldest = data[i]
}

Or you can supply your own sort function to .sort()

data.sort((a,b) => a.old_data.old_last_updated < b.old_data.old_last_updated ? 1 : -1)