You can use the group block to add a background to any block on the page.
- Select the block, then either in the List View or the buttons above the block in the editor, click the three dots, then “Group”.
- In the right sidebar, uncheck “Inner blocks use content width”
- Directly above that checkbox, click the half-filled circle, which opens the styles menu.
- Select “Background” and then select a color from your color palette. You’ll now see the background color applied to your group, but it isn’t full width yet.
- Directly above the group in the content editor, click the Alignment button and select “Full Width”.