WordPress block themes include a layout setting that provides two essential key/value pairs for setting the content width:

• contentSize, which establishes the default width for blocks in both the editor and the front end
• wideSize, which activates the wide-width feature and sets the width for wider blocks

In Powder, the values for these are 640px and 1280px, respectively. These widths can be set using two different methods: via theme.json (Code) and through the Site Editor (No-code).

Set Content Width (CODE)

Below is the code used to set content widths in theme.json:

{
	"settings": {
		"layout": {
			"contentSize": "640px",
			"wideSize": "1280px"
		}
	}
}

Additionally, fluid typography settings should changed to match:

{
	"settings": {
		"typography": {
			"fluid": {
				"maxViewportWidth": "1280px",
				"minViewportWidth": "640px"
			}
		}
	}
}

Set Content Width (NO-CODE)

Go to Appearance > Editor > Styles > Layout, and you will see a panel like the one below. Change the values for Content and Wide as desired.