How to calculate the distance of an object with velocity?

Most of the trajectory equations can also be found here. I'm not 100% sure whether you're trying to get the horizontal distance or the arc length, so I've included both, and luckily Mathf has all the functionality we need:

 private static float GRAVITY = 9.8067f;
 
 public static float GetHorizontalDistance(float velocity, float launchAngle, bool degrees = false)
 {
     // convert to radians if necessary
     if (degrees)
     {
         launchAngle *= Mathf.Deg2Rad;
     }
 
     return (velocity * velocity * Mathf.Sin(2.0f * launchAngle)) / GRAVITY;
 }
 
 public static float GetArcLength(float velocity, float launchAngle, bool degrees = false)
 {
     // convert to radians if necessary
     if (degrees)
     {
         launchAngle *= Mathf.Deg2Rad;
     }
 
     // pre-calculate sine and cosine of launchAngle and square of velocity
     float sinAngle = Mathf.Sin(launchAngle);
     float cosAngle = Mathf.Cos(launchAngle);
     float vSquared = velocity * velocity;
 
     return (vSquared * (sinAngle + cosAngle * Mathf.Log((1.0f + sinAngle) / cosAngle))) / GRAVITY;
 }

You may need to swap out the const GRAVITY for Unity's value, depending on your usage case.