Image: Dufour Map, first edition, 1845-1865, from the federal geoportal
In QGIS, you can add all the layers from the federal geoportal (map.geo.admin.ch) to your project. Once you have established a connection to the Web Map Service of Swisstopo, you are ready to use the layers in all your QGIS projects.
The following tutorial shows you how to proceed: