MS Word for Imac M1 ??

MS has not sold single MS Office apps in a very long time, maybe 20 years. Your new iMac has Apple's Pages, a standalone word processor. Otherwise you need to buy the subscription-based Office 365. I do not know if the non-subscription Office 2019 is still available.

EDIT: Loks like Office 2019 is still available: https://www.microsoft.com/en-us/microsoft-365/p/office-home-student-2019/cfq7ttc0k7c8/?activetab=pivot%3aoverviewtab

Also Either Office 365 or Office for Mac 2019 will run fine on the new M1 iMacs. The new M1 based Macs support Rosetta 2 which allow Intel based apps to run on the new M1 processor, finally MS has announced native M1 support but I don't know if it has been released yet.

If you don't know what Rosetta 2 is please click https://support.apple.com/en-us/HT211861

LibreOffice is free.

https://www.libreoffice.org/

There’ve been threads here where Office users have used LibreOffice to access Office documents Office couldn’t, too.