Does a binary node inherit the interface of a non-binary node?

Question

OOP

Wrote the basic node interface.

interface NodeInterface
{
    public function key();
    public function value();
    public function __construct($key, $value);
    public function contains(NodeInterface $node): bool;
    public function addChild(NodeInterface $node);
    public function setParent(NodeInterface $node);
    public function parent(): ?NodeInterface;
    public function children(): array;
    // ...
}

By implementing the Node class based on it, we get a typical node with many children. OK.
But here, let's say, you need to write a binary node class for a binary tree.
There can be only 2 subnodes: left, right. How to implement?

1. Inherit from Node and set hard limits:
   

   interface BinaryNodeInterface extends NodeInterface
   {
       public function left(): ?BinaryNodeInterface;
       public function right(): ?BinaryNodeInterface;
   }
   
   class BinaryNode extends Node implements BinaryNodeInterface
   {
       public function left(): ?BinaryNodeInterface
       {
           return $this->children[0] ?? null;
       }
   
       public function right(): ?BinaryNodeInterface
       {
           return $this->children[1] ?? null;
       }
   
       public function addChild(NodeInterface $node)
       {
           if (count($this->children) < 2) {
               parent::addChild($node);
           }
       }
   }

   
   But then the substitution principle from SOLID is grossly violated.
   
2. 
   Make two different basic interfaces like MultiNodeInterface and BinaryNodeInterface, but then you get code duplication and is not universal.