Change the excerpt length

// Set automatic excerpts to 30 words (WordPress default: 55).
add_filter(
	'excerpt_length',
	function () {
		return 30;
	},
	999
);

What it does

When a post has no hand-written excerpt, WordPress makes one from the first 55 words. On blog grids that's often too long.

This snippet sets the length to 30 words. Change 30 to the number you want.

Good to know

• It only changes automatic excerpts, not the ones you type in the Excerpt box.
• In block themes, the Excerpt block has its own "Max number of words" setting, and that setting wins.