Hello,
I think this is Windows/Microsoft specific. If you want your own toolbars with fixed height (and width as you ask in other postins), you should perhaps consider to follow a different approach. Maybe you can use something like a dialog toolbar?
I use a docking toolbar which has a CDialogEx inside. I don't have problems with the sizes when the dpi changes. Have a look at the link I gave you many times in your other questions already. It is easy to implement and you have total control of the toolbar.
https://www.codeproject.com/Articles/493218/Understanding-CDockablePane
Regards, Guido