In KDE, you should be able to resize the panel with an arrow on the left and right side. When I installed KDE, it already had some Artix theming so I think that has something to do with the arrows not being there. You're supposed to see this https://userbase.kde.org/File:Panel_Settings.png but, I see this https://imgur.com/gallery/HBP8Uzb (Sorry for bad picture). Any idea on how I can add this?
so, just switch to another theme (default breeze) and look if the arrow are on side (i have it in breeze). Probably is that artix's theme bug.