I'm not quite clear about what you're saying.
The Outlook.pst file gets updated everytime you use Outlook so it will always have the latest date and time. If you have Outlook open when you try to do the copy it wont let you. So, just close Outlook and you'll be able to copy it. I've just tried it to confirm it works and it does.
So again this Outlook file will contain all your emails, contacts and calendar etc. There isn't a seperate folder/file for these. However, should you want there is an option under the Files menu in Outlook called Open and Export. It will allow you to export specific things that you choose. For example you could export your contacts as a CSV file to be read by Excel or imported into another program.
However, if its just a backup you need for safety then just backup the whole Outlook folder I mentioned previously.
The copy of Office 2019 (or Office 2021) that you can buy on Amazon is downloaded from MS. Just save the download to a folder to keep for as long as you like and its a perpetual license - no subscription. Just like having the disks.
Another Email app that I've used and recommended to some who don't want Outlook is Thunderbird
https://www.thunderbird.net/en-GB/
Its free and from memory it can import the PST file created by Outlook.
Libre Office is Ok but after years of using MS products I didn't like it - just different thats all.