create a unity script bullet velocity trajectory predictor Line with LineRendererJobs.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class BulletVelocityTrajectoryPredictor : MonoBehaviour {

public float speed; //speed of bullet
public Vector3 startPosition; //starting position of bullet
public Vector3 direction; //direction of bullet

public int lineSegmentCount = 10; //number of segments in trajectory line
public LineRenderer lineRenderer; //LineRenderer component

// Use this for initialization
void Start () {
    lineRenderer.positionCount = lineSegmentCount;
    PredictTrajectory();
}

// Update is called once per frame
void Update () {
    PredictTrajectory();
}

//Predicts trajectory of bullet
void PredictTrajectory()
{
    Vector3 velocity = speed * direction; //velocity of bullet

    Vector3 previousPosition = startPosition;
    for (int i = 0; i < lineSegmentCount; i++)
    {
        //Predict next position
        float time = (float)i / (lineSegmentCount - 1);
        Vector3 nextPosition = CalculatePositionAtTime(time, startPosition, velocity);

        //Draw line segment
        lineRenderer.SetPosition(i, nextPosition);

        //Update previous position
        previousPosition = nextPosition;
    }
}

//Calculates position at given time
Vector3 CalculatePositionAtTime(float time, Vector3 startPosition, Vector3 velocity)
{
    //Calculate gravity vector
    Vector3 gravity = Physics.gravity;

    //Calculate position
    Vector3 position = startPosition + time * velocity + 0.5f * gravity * Mathf.Pow(time, 2);

    return position;
}

}