A lot of things.

app/Http/Requests/StoreDraftRequest.php

@@ -0,0 +1,26 @@
+<?php
+
+namespace App\Http\Requests;
+
+class StoreDraftRequest extends StoreEntryRequest
+{
+    public function rules(): array
+    {
+        $rules = parent::rules();
+        $rules['submit-state'] = 'required|string|in:draft';
+
+        $rules = array_map(function($rule){
+           if( is_array($rule) ){
+               return array_map( fn($r) => $r === 'required' ? 'nullable' : $r, $rule);
+           }
+
+           return preg_replace(
+               ['/\brequired_without\S*/', '/required_with\S*/', '/\brequired\b/'],
+               ['nullable',                 'nullable',           'nullable'],
+               $rule
+            );
+        }, $rules );
+
+        return $rules;
+    }
+}