Be certain to have a last Mojave Time Machine backup before upgrading to Catalina, and do not resuse that same backup drive for Catalina.
Office 2011 for Mac is a 32-bit application suite and definitely will not run on Catalina which requires 64-bit on applications. The single-purchase Office 2019 for Mac is 64-bit and compatible with Catalina. Just do not install any 32-bit helper plug-ins into these applications.
I would completely uninstall Office 2011 for Mac, and then install Office 2019 for Mac — before the upgrade. Also, check other third-party applications with there vendors for availability of 64-bit support, and this goes for printer and scanner drivers which are likely to still be 32-bit. See if there is an uninstaller in the Applications/Microsoft folder. If not then this Microsoft article on complete Office 2011 for Mac removal may help.
With Catalina, it is very important to apply new released updates for Office 2019 for Mac as they become available.