what would be the outcome if I requested a Win 10 free upgrade?
That wouldn't be an option, as such, but.....
I think the goal is to upgrade your current version of Windows 10 build 10240 to the newer version of Windows 10 build 10586, which....
As I noted above is available from
https://www.microsoft.com/en-us/software-download/techbench
You should probably first confirm which build you have installed.
IF you right click the start button and choose run and in the run dialog box type
winver
hit enter or click OK
you should see something like this.....
Your particular Version / OS Build number is what you need to determine before you attempt any further action, except....
Backing up all your critical data and or creating a disk image, which are always good to have on hand regardless.