create custom page template

templates/page-brochure.html

@@ -1,6 +1,5 @@
 <!-- wp:group {"layout":{"type":"default"}} -->
-<div class="wp-block-group">
-  <!-- wp:template-part {"slug":"header","theme":"lex-scotland-theme","tagName":"header"} /-->
+<div class="wp-block-group"><!-- wp:template-part {"slug":"header","theme":"lex-scotland-theme","tagName":"header"} /-->
 
   <!-- wp:group {"style":{"spacing":{"padding":{"right":"0","left":"var:preset|spacing|80"}}},"layout":{"type":"default"}} -->
   <div class="wp-block-group" style="padding-right:0;padding-left:var(--wp--preset--spacing--80)">

theme.json

@@ -376,5 +376,14 @@
         }
       }
     }
-  }
+  },
+  "customTemplates": [
+    {
+      "name": "page-brochure",
+      "postTypes": [
+        "page"
+      ],
+      "title": "Brochure"
+    }
+  ]
 }