MacOS Mojave Installer File

I am attempting to download MacOS Mojave to create a bootable USB disk but the only available file is the most recent update...

Am I doing something wrong?

Whenever I try to follow a link to Mojave installer file, the updater in system preferences takes over and tries to re download the most recent update 10.14.6 - No option for the complete installer.

Am I just out of luck or just missing something?

I plan to update my Late 2012 iMac 27" 3.4 i7 with 2 SSD's to replace the 1Tb fusion drive currently installed and failing....

I would prefer to be able to reinstall Mojave via the installer USB instead of using a slow internet connection. I am reluctant to upgrade to Catalina due to current software usage, but it it is the only way.........

Thanks in advance for anyones help.

JPSchmid