Agreed that some screen elements can look small on a 4K monitor, but since you're spending all of your workdays in Qt Creator, eventually you'll learn all the keyboard shortcuts and perhaps introduce some of your own (at least I have).
By then you'll permanently hide the menu with Ctrl+Alt+M and don't mind small-sized elements on the screen because they're fixed/static and you know them very well by heart anyway. My own C++ code, of course, that needs to visible and some days I'll increase the font size :-)