Big Sur and now being told I need to pay $70 a year for Microsoft 365- is that my only solution to opening a word doc or excel

Another very good option is the free, open-source LibreOffice. It can open, edit and save MS Word documents in MS Word format or it's own format. It's more compatible with MS Office files than the Apple apps are.

Pages and Numbers can open simple documents/spreadsheets.

There is also Open Office and LibreOffice.

There is a paid subscription option for the desktop version of Microsoft Excel, OneNote, PowerPoint and Word at $9 per month if you want to keep your Microsoft Excel, OneNote, PowerPoint and Word updated to the latest versions all the time.