Hey Maltastudio.
Scaling the font size under control panel definitely makes all text, including the playlist, larger. I see you are running Win 10, so right click on the windows start menu button in the bottom left of the desktop (or wherever you have it) and choose control panel, then click on display. On the window that opens, under the heading 'change size of items, click on the linked text that says 'set a custom scaling level'. In the drop down box choose a percentage (try 150% for a start), then click OK on that dialogue box, then apply on the next screen. A pop-up will tell you that you need to sign out to apply the settings. Click 'sign out now' . When you sign back in, your playlist text, along with everything else will be bigger.
Definitely let me know if you find a custom setting for it in an ini fiile anywhere. That would be great:)