How I can do knockback without OnColisson or OnTrigger

did you forget to include the script? It's not in your post.

If I understand, you do NOT want to use OnTrigger or OnCollision.

Another option would be use a raycast from the center/core part of whatever enemy collider will be making contact with the player. You'd have to do this in Update, so a raycast every frame and see if and where the raycast hit the player. You'd just raycast from the enemy to the player and if the hit distance was, for example 0.1 (or some distance to indicate they're so close that they've collided). However you won't be able to get fined-grained collision info (like an enemy hand hitting a player's head) unless you use OnColisionEnter.

Só I try with add force but no worked so well this is my script using System.Collections; using System.Collections.Generic; using UnityEngine;

 public class HandleMovement : MonoBehaviour {
 
     Rigidbody2D rb;
     StateManager states;
     HandleAnimations anim;
 
     public float acceleration = 30;
     public float airAcceleration = 15;
     public float maxSpeed = 60;
     public float jumpSpeed = 5;
     public float jumpDuration = 5;
     float actualSpeed;
     bool justJumped;
     bool canVariableJump;
     float jmpTimer;
 
     void Start () 
     {
         rb = GetComponent<Rigidbody2D>();
         states = GetComponent<StateManager>();
         anim = GetComponent<HandleAnimations>();
         rb.freezeRotation = true;
     }
     
     void FixedUpdate () 
     {
         if(!states.dontMove)
         {
             HorizontalMovement();
             Jump();
         }
         if (states.gettingHit && states.onGround && justJumped == false && states.canAttack)
         {
             if (states.lookRight)
             {
                 rb.AddRelativeForce(Vector3.left * 13);
                 states.dontMove = true;
 
             }
             else
             {
                 rb.AddRelativeForce(Vector3.right * 13);
             }
         }
     }
     void HorizontalMovement()
     {
         actualSpeed = this.maxSpeed;
 
         if(states.onGround && !states.currentylAttacking)
         {
             rb.AddForce(new Vector2((states.horizontal * actualSpeed) - rb.velocity.x * this.acceleration,0));
 
         }
         //caso esta sliding
         if(states.horizontal == 0 && states.onGround)
         {
             rb.velocity = new Vector2(0, rb.velocity.y);
         }
     }
     void Jump()
     {
         if(states.vertical >0)
         {
             if(!justJumped)
             {
                 justJumped = true;
 
                 if(states.onGround)
                 {
                     anim.JumpAnim();
 
                     rb.velocity = new Vector3(rb.velocity.x, this.jumpSpeed);
                     jmpTimer = 0;
                     canVariableJump = true;
                 }
             }
             else
             {
                 if(canVariableJump)
                 {
                     jmpTimer += Time.deltaTime;
 
                     if(jmpTimer < this.jumpDuration / 1000)
                     {
                         rb.velocity = new Vector3(rb.velocity.x, this.jumpSpeed);
                     }
                 }
             }
         }
         else
         {
             justJumped = false;
         }
     }
 
     public void AddVelocityOnCharacter(Vector3 direction, float timer)
     {
         StartCoroutine(AddVelocity(timer, direction));
     }
 
     IEnumerator AddVelocity(float timer,Vector3 direction)
     {
         float t = 0;
 
         while(t<timer)
         {
             t += Time.deltaTime;
             rb.AddForce(direction * 2);
             yield return null;
         }
     }
 
 }