Learn how to keep the border/stroke width the same size when creating different-sized objects. It’s very easy and essential to know how to do this in Inkscape.
In order to have stroke width the same, you need to make sure that the option “When scaling objects, scale the stroke width by the same proportion” at the top is not active. It will be a lighter color than the others when not active. Once disabled this option scaling won’t change the stroke width anymore.
This is a global change and will affect any other object that has a stroke you create going forward. Of course, if you no longer want this effect just enable the option again and stroke will be affected by scaling agian.