Can I update iWorks (Pages, Numbers, etc.) without updating my OS to Catalina (my old MacBook can't )

You will need at minimum, macOS Mojave (or later) to download the Pages, Numbers, and Keynote applications that are presently (2019-12-09) in the Mac App Store. Apple does not have past, full installers for these applications available for download.

https://support.apple.com/kb/SP777?locale=en_US

https://itunes.apple.com/us/app/macos-mojave/id1398502828?mt=12

Or...

Look into the Free LibreOffice, it handles MS Office files…

https://www.libreoffice.org/

Apple macOS (Mac OS X)

The software and hardware prerequisites for installing on a Apple macOS computer are as follows:

• LibreOffice 6.3.x: macOS 10.10 (Yosemite) or higher

• LibreOffice 6.2.x: macOS 10.9 (Mavericks) or higher

• Intel processor

• 512 MB RAM

• Up to 800 MB available hard disk space

• 1024x768 graphic device with 256 colors (higher resolution recommended)

It is a recommended best practice to back-up your system and data before you remove or install software.

Notes:

• For certain features of the software - but not most - Java is required. Java is notably required for Base.

• Due to an issue, there are the following restrictions with Java: on macOS 10.10 and newer, JRE isn't found, JDK is required

• LibreOffice 4.3 can still run on OS X 10.6+, but please understand that this support ended when 4.3 was retired on May 27, 2015.

https://www.libreoffice.org/get-help/system-requirements/#Apple

Feature Comparison of LibreOffice v6.3 with Office 365/Office 2019 for Mac

https://wiki.documentfoundation.org/Feature_Comparison:_LibreOffice_-_Microsoft_Office

If your MacBook Pro was introduced in 2012, then you can upgrade to Mojave. Section 4 of the preceding web page has a section 4 that provides a link to Mojave download in the Mac App Store.

Double-check with at the third-party vendor websites that their applications, and printer/scanner/mfp drivers are compatible with Mojave, or that your wired/wireless device is supported by Apple's AirPrint, which would not require vendor drivers.

How to download mojave now? (there is only update of catalina in app store)