If you have set the XFCE scaling and GDK scaling up (to 1.5 or 2 ) you can choose or download a other UI Pack for Libreoffice. Libreoffice support themes that will better match for High-DPI https://wiki.archlinux.org/title/LibreOffice#Theme. For the application unison-gtk I have no idea.
Link how to setup XFCE and GTK3 for high-dpi: https://wiki.archlinux.org/title/HiDPI#Xfce
Hope that helps a little bit.