Massive Textual content in Unity Inspector

Utilizing the PropertyDrawer as proposed by @DMGregory lastly works:

utilizing UnityEditor;
utilizing UnityEngine;

[CustomPropertyDrawer (typeof (LargeTextInGUI))]
public class LargeTextInGUIDrawer : PropertyDrawer
{
    public override void OnGUI (Rect place, SerializedProperty property, GUIContent label)
    {
        var fashion = new GUIStyle ();
        fashion.fontSize = 40;
        EditorGUI.LabelField (place, label.textual content, property.intValue.ToString(), fashion);
    }

    public override float GetPropertyHeight (SerializedProperty property, GUIContent label)
    {
        return 45;
    }
}

utilizing UnityEngine;

public class LargeTextInGUI : PropertyAttribute
{
}

public class MyClass: ScriptableObject{
    [LargeTextInGUI]
    public int currentState;
}