calculate launch velocity needed with drag and custom gravity

Hi. I am currently trying to send a physics ball towards a specific target, simple and there are a lot of answers already here, so I found this script:

 void SendToTarget(Vector3 target) {      
         Vector3 p = target;
 
         float gravity = Physics.gravity.magnitude;
         // Selected angle in radians
         float initialAngle = 50;
         float angle = initialAngle * Mathf.Deg2Rad;
 
         // Positions of this object and the target on the same plane
         Vector3 planarTarget = new Vector3(p.x, 0, p.z);
         Vector3 planarPostion = new Vector3(_rigidbody.transform.position.x, 0, _rigidbody.transform.position.z);
 
         // Planar distance between objects
         float distance = Vector3.Distance(planarTarget, planarPostion);
         // Distance along the y axis between objects
         float yOffset = _rigidbody.transform.position.y - p.y;
 
         float initialVelocity = (1 / Mathf.Cos(angle)) * Mathf.Sqrt((0.5f * gravity * Mathf.Pow(distance, 2)) / (distance * Mathf.Tan(angle) + yOffset));
 
         Vector3 velocity = new Vector3(0, initialVelocity * Mathf.Sin(angle), initialVelocity * Mathf.Cos(angle));
 
         // Rotate our velocity to match the direction between the two objects
         float angleBetweenObjects = Vector3.Angle(Vector3.forward, planarTarget - planarPostion) * (p.x > _rigidbody.transform.position.x ? 1 : -1);
         Vector3 finalVelocity = Quaternion.AngleAxis(angleBetweenObjects, Vector3.up) * velocity;
 
         // Fire!
         _rigidbody.velocity = finalVelocity;
     }

my ball never reaches the target because of 2 things: a) its got a drag value of 1 b) its got a custom gravity script on it that will push the ball down all the time and even more when its falling (velocity.y < 0). here is the snippet for that:

 sphere.velocity += Vector3.up * Physics.gravity.y * (gravity - 2) * Time.deltaTime;
 
             if (sphere.velocity.y < 0) {
                 sphere.velocity += Vector3.up * Physics.gravity.y * (gravity - 1) * Time.deltaTime;
             }

so my question now is: how can i send the ball with a drag of 1 and this custom gravity script towards a specific target using physics? thanks!