I couldn't find a way from within the Drake program to make the Client Manager text larger, but I can do this by adjusting the Windows setting for scale. It will, however, make all of your icons and fonts larger, and you may not like that. It's easy enough to go back if you decide that a change in this setting isn't to your liking.
An easy way to find this is while on the main Windows desktop, right click in a blank space that will bring up a popup box, and then click on "Display Settings" there. That will launch a page where display adjustments are made. The option you are looking for to change is under "Scale and Layout" that is probably set to 100% (recommended). If you adjust that to a higher percentage, your Client Manager within Drake should appear larger. It will also enlarge your desktop icons and text within other apps. You'll have to try this to see if it is bothersome in other programs.