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Most of the full width options are available without the Plus plugin.
If you just want the whole site to be full width, go to Main options > Wrapping areas > Wrapper Area > Align Area > choose “Align full” in drop down list
If you want to only extend some parts of the site like header, footer, menus…. Go in the settings of that area, and in the “Align Area” option drop down list choose “Align Full”