To download windows 10 ISO file from Microsoft official site ,you need to follow these steps :
Step-01 :
Go to google search and search for → Microsoft windows 10 ISO
open the 1st link (Microsoft.com)
Step-02 :
Click on Download Tool Now → this will download a file called “MediaCreationTool21H2”
Step-03 :
Run the file → press accept (license agreement) → check : Create installation Media → Next
Step-04 :
Check : use the recommended options for this PC → next
Step-05 :
Check : ISO → Next
Step-06 :
choose a location for you ISO file
Step-07 :
Once it is over , Click to open the location of the ISO file
If you missed a step you can check the next video
Check also , How to use the ISO file and copy it to a USB flash drive to make a windows 10 installation USB