Windows 10 Will Installing Windows 10 Move D Drive Files to Windows.old on C Drive?

it will try to install to c drive by default... making the old Windows folder to store the old copy and will not touch your D drive unless you actually tell it to install to that instead

however, if you have both an old spinning rust drive and a ssd it will default to the older drive [ignores the ssd] and make that the new C drive... if you want to install to a newer drive type then temp remove the other drives [unplug them] until after the install so Windows defaults to whatever is remaining