Layout
Every Partna sitepage renders through the same layout, so there's no layout setting in the design editor. Design is about your kit: theme, colours, type, spacing and shape.
Partna uses a single layout for every sitepage: full-screen panels, one per section, that visitors scroll through in order. How it works for a visitor is covered in The layout.
Because the arrangement is fixed, the design editor focuses entirely on how your page looks: the theme mode behind the whole page, your colours and typography, and your spacing, corners and borders. Change any of them and every panel re-renders to match, your content never moves and never needs re-entering.