Q: How to control the height of the title bar in xfce? How can I control the height of the title bar in xfce?
I only have medium experience with linux desktops, I could change some settings in a text file or install a package, but an instruction that would outline the major steps would be great.
I could not find an answer that I could understand or follow to this question during my searching.

A: Go to Settings > Window Manager > Style (first tab)
The height of the title bar in XFCE depends on the "Theme" you choose.

A: I found out it is not possible by changeing some numerical height value, because the height of the window title bar is not dynamically generated. It is drawn based on a graphical element that is part of the theme and this has a fixed height. 
To do what I was asking for, it would be necessary to create a new theme that has the desired proportions.
There are also "compact" themes that have more space because they draw some elements smaller, but they are hard to find and it is still not as small as I would like. 

A: I solved this issue by editing the xpm-files in /usr/share/themes/
xpm-files can be edited in a text editor.

A: Navigate to ~/usr/share/themes/, find the folder for the theme that you want to change (Greybird-dark in my case) and edit the themerc.txt file in that folder in a text editor opened as root.
The parameters that you want to set/change are detailed here. Replacing defaults where needed, I added
frame_border_top=10
title_vertical_offset_active=6
title_vertical_offset_inactive=6
button_offset=6
button_spacing=2

Once you are done, exit the text editor. Then, change your theme to something else and then change back to the one that you've just changed. That should activate your changes.
Note that these settings will sometimes be overwritten by significant upgrades. For example, I lost them to the Xubuntu 20.04 -> Xubuntu 22.04 jump.
