✅ 3 objects inheritance thing + force call base.DoThing();

public class Class3 : Class2 {
     public ... void DoThing() { // any way????
          //I would also want to forcely call Class2's DoThing without the programmer removing the base.DoThing();
          //code
     }  
}

public class Class2 : Class1 {
   public override void DoThing() {
       //code
   }
}

public abstract class Class1 {
   public abstract void DoThing();
}