Yes, uhm, here.
WinSCP VS default Windows font size
After checking, it appears that the file names are of the same size (even though for some reason they definitely feel smaller), while the things that are in a different font (such as the directory tree and the (not shown) list of stored sessions) are a little bit smaller.
Compared to Windows' default text size, that is. However, contrary to WinSCP's, almost every text size in Windows can be customized individually, which is what I did with mine after taking this screenshot and discovering the option, taking the font sizes from minimal to comfortable. But this, sadly, doesn't solve the problem with WinSCP
There IS an option that affects everything including WinSCP, but that makes pretty much everything huge, uselessly so (normal since it's more of an "accessibility" option), not to mention it makes several things "display funny" because they're not made for being "forced bigger" like that.
Also, you can see on the same screenshot the difference between WinSCP's, Windows Explorer and Firefox's (default theme) icons. Windows Explorer icons (those meant to be clicked, not those that indicate what the file is) are generally larger, even if not significantly larger, and if they're not (e.g. the file history button on the right) they're placed in a practical way so that they don't look like a tiny little tile among a bunch of others. Firefox has a one-line display for its icons like WinSCP. Of course, there aren't as many, but it shows what I want to express: when button icons are in a uniform kind of display, in one line, they need to be at least a bit larger, or else they feel impractical to use.
Lastly, an additional comparison screenshot, with my current configuration.
WinSCP vs customized Windows font size
Sadly, "System" theme or not, custom settings do not affect WinSCP, apart from the menu bar. (I tested with a super huge font size to make sure, too.)
As a conclusion, I'm not saying WinSCP is "faulty" because of these size issues. Just that having the option of customizing the size would be very comfortable. I may be the first one actually complaining about it, but I don't think I'm the only one who would be more comfortable with something a bit larger.[/i]