// sur ton child collider detector : --------------------------------

void OnTriggerEnter2D(Collider2D other)
{
    if (!other.CompareTag("Player")) return;

    enemy.Activate();
}

// sur ton enemy -----------------------------
    bool isActive;

    public void Activate()
    {
        if (isActive)
            return;

        isActive = true;
    }
public void Deactivate()
{
    if (!isActive)
        return;

    isActive = false;
}
void OnTriggerEnter2D(Collider2D other)
{
    if (!other.CompareTag("Player")) return;

    PIF PAF POUF
}