themes-wordpress/geologist/sass/templates/_index.scss

.wp-block-post-featured-image {
	margin-top: 0;
}

/* Add some extra space if there's no post title present. */
.wp-block-post-date + .wp-block-group > .wp-block-post-featured-image,
.wp-block-post-date + .wp-block-group > .wp-block-post-excerpt {
	margin-top: calc(2 * var( --wp--style--block-gap ));
}