Hi Rajkumar
Microsoft only directly provide the latest version (1909)
Click this safe link to download the Windows 10 ISO in any version, including 1809, those ISO's are sourced directly form the Microsoft Servers
https://tb.rg-adguard.net/public.php
If you need to create bootable installation media on a USB form the ISO, use Rufus to create that:
https://rufus.ie/
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Standard Disclaimer: This is a non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.
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