Geometry - Scaling in Inkscape
Scale tab of the Transform dialog (Object → Transform… (Shift+Ctrl+M)).
With the handle of the bounding box, see Inkscape - Bounding Box (Selection cue)
When an object(s) is selected
- < and >: Default scales by 2 px
- Shift + < and >, you scale by 20 px
- Ctrl + < and >: scale up or down to 200% or 50% of the original, respectively.
- Alt + < and >: scale by 1 pixel at the current zoom (i.e. by 1 screen pixel)