In addition to @mook765's excellent suggestion of installing the Libreoffice
snap, it is also available as a
flatpak, which has the advantage of a much quicker startup time.
Snaps are getting much better, but the startup time when you open the application can still be noticeably long.
In order to use flatpaks you have to install
flatpak, which is available in the Ubuntu repositories:
sudo apt install flatpak
You can add the plugin to integrate with Ubuntu Software Center, if you use it:
sudo apt install gnome-software-plugin-flatpak
And finally install flathub:
flatpak remote-add --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo
Once that's done, you can install flatpaks, for LibreOffice it would be:
sudo flatpak install org.libreoffice.LibreOffice