Post type specific patterns appear when creating new posts of designated types, like page patterns that appear when creating new pages. These patterns are technically block-type patterns targeting the post content block.
The key is the postType argument that makes patterns appear in the pattern selection modal when creating new content. This provides users with starting points tailored to specific content types.
Examples include different page layouts for various purposes, post templates for different content styles, or landing page patterns for marketing content.
This targeting approach helps users start with appropriate layouts rather than blank pages, speeding content creation while maintaining design consistency.