Unity Mathf.lerp

Constant

// constant movement
void Update() {
    transform.position = Vector3.Lerp(pos1.position, pos2.position, speed * timer);
    
    if (destination == pos1) {
        timer = Mathf.Clamp(timer = Time.deltaTime, 0.0f, 1.0f/speed);
    } else {
        timer = Mathf.Clamp(timer + Time.deltaTime, 0.0f, 1.0f/speed);
    }
}

Smooth

// accelerates then slows down.
void Update() {
    transfrom.position = Vector3.Lerp(transform.position, 
                                        destination.position,
                                        speed * 3.0f * Time.deltaTime);
}