Thank you for your question.
Breda template was created in adaptive layout. That means for each device (desktop, tablet, mobile) you create a different design. Breda theme comes with desktop and mobile layouts by default. You can create a responsive layout from this template if you want. You need to activate responsive features on the pages, add breakpoints and adjust everything for each breakpoints (this is how responsive websites are built in Muse).
I hope this helps.