custom tab in preferences (editor-script)

You can create one such tab using the PreferenceItem attribute.

Because the docs only have an example in JavaScript, here is one for C#...

 using UnityEngine;
 using UnityEditor;
 
 public class CustomPreferences
 {
     // Have we loaded the prefs yet
     private static bool prefsLoaded = false;
     
     // The Preferences
     private static bool boolPreference = false;
 
     [PreferenceItem("My preferences")]
     private static void CustomPreferencesGUI()
     {
         if (!prefsLoaded)
         {
             boolPreference = EditorPrefs.GetBool("BoolPreferenceKey", false);
             prefsLoaded = true;
         }
 
         EditorGUILayout.LabelField("Version: x.xx");
         boolPreference = EditorGUILayout.Toggle("Bool preference: ", boolPreference);
 
         if (GUI.changed)
         {
             EditorPrefs.SetBool("BoolPreferenceKey", boolPreference);
         }
     }
 }