Pages

Fill shapes and text boxes with colour or an image in Pages on Mac
You can fill shapes and text boxes with a solid colour, gradient (two or more colours that blend into one another) or image.

If you want to use the same formatting for other objects, you can create your own style to use again.
Tip: You can also change the colour of lines, shadows, borders, text and more; whenever you see a colour well in the sidebar, you can click it to add colour to whatever is selected on the page.