Since WordPress version 6.3, it is possible create and manage your site’s Patterns and template parts via the Site Editor’s sidebar. You can learn about the Site Editor in this support article: Site Editor.
The Site Editor Patterns menu is only available when you install and activate a Block theme on your site.
Working with patterns
Navigate to Appearance > Editor > Navigation to access your Patterns and template parts.
Please note that template parts are now listed under Patterns.