Google Docs - FTW. It can do everything you might want in Word, plus you can collaborate on documents in real time, something that I think Office 365 allows.

Google Docs is free. So is Google Sheets (Excel alternative) - also real-time collaborative in case you wanted to organize something like a tennis team, for example.

Google Drive allows sharing of files or folders. Google Forms is nice if you want to collect information from multiple people.

Google Slides - I have not actually used this in a long time. But it works fine.

All of the Google products work on PCs, Macs, Chrome Books, Linux, smart phones, tablets, etc.

All of the products mentioned are Free. (As in free beer, not as in free speech.) You really can't go wrong with it. You don't need to worry about upgrades. You can also share them with others without worrying whether they use PC, Mac, phone, etc. It will "just work".

I use Stack Social to purchase many PC applications. I purchased Office 2021 for 39.00 for each of my PC's and dumped the office 365 subscription every year. It is a 1 PC lifetime license.
These are all 100% legit apps. The site is well known in the computer geek world, lol. Don't pay 150.00-200.00 for the same thing.
StackSocial: The Hottest Tech Deals, Delivered Daily
However as others have said, your Office apps are not going to stop working.
I still have an old Windows 7 machine that has the old Office on it and all the Office apps still work fine.
You just don't get new updates/features, but who care if you are just doing basic Word/Excel stuff.

Microsoft Office via Keysoff.com
 

You can buy a key to MS Office from Keysoff.com. I regularly do this. My current version is Office 2024. It is legitimate. They buy keys from companies that purchase computers loaded with Office who do not use Office. I believe I paid about $35 for my Office 2024 version.

I believe unsupported means you won’t get updates for the software but can still use it. I’ve been using old MS office software from 2005 and it still works on windows 11.

There have been a few things mentioned. 1st you can still use your existing office product, 2nd 365 has both cloud/web version and desktop install version for $99 per year which isn't all that bad a deal.

As for going "off brand" i have words of caution. in some cases, you can end up 'unsupported' meaning that 'off brand' i.e., google etc will claim your problem is MS and MS will say it's the other product. MS is a bit crafty there are pieces of Windows that are coded to basically cause issues with competition. Especially Google.

Simple advice, and yes I'm a MS certified trainer so it's a bit bias maybe, it's easier to do option 1 or 2

Free Office
 

Free Office in the Internet:
Free Microsoft 365 Online | Word, Excel, PowerPoint

Don’t bother with the non-Microsoft office suites unless you want to fight the strange formatting and other “close, but not right” issues. Also the learning curve can be an issue with the knock-offs.

Also, using the unsupported version or buying from Stack Social are good options.

It seems to me that Microsoft could easily prevent the use of counterfeit or obsolete products if they wanted to do so. Apparently, they don't want to, so they must be making money in another way.

Note that when Sony tried to prevent people from copying their music CDs, it didn't work out well for them.

ProductKeys.com sells a full version of Microsoft Office Professional 2024 for $21 (no, that's not a typo). It's not a subscription, it's the full version and is good for the life of your computer. I bought one for both of my laptops.

If you have an iPhone or iPad you already have access to Apple's suite of Pages, Numbers, Keynote and others. You can access them in your iCloud account. Those applications can open, read and save to .docx very easily.

I got off the MS merry-go-round after XP went away and went to Apple. Never looked back.

Using software no longer supported leaves your computer at risk. Without the support, you are not receiving updates that protect the computer from viruses, spyware and other malicious software.

A little off topic, but where can one get a refresher course on Office. I used spreadsheets years ago and now have a need to use them again.
Thank you.

I have Office 2003 that I use on my burner laptop. It has a compatibility update that allowes it to open, edit, and save the later Office file formats. I installed OpenOffice on my kids' computers and they had no problems with it. I have to use Google Docs for work stuff these days and, after I got used to its slight differences, it works fine too.

That advice is mainly for the operating system.
For Office, just disable scripts, java, and macros. Then you are fine. Nothing malicious has ever been identified that works without scripting enabled.

Open Office. It is open source, secure, works as well as or better than MS Office, and it is free.
It comes with some goofy foreign language fonts, but you can port your true type fonts from your old MS Office installation.