How to add equal force across multiple platforms

My problem is that when I add force like this

rigidbody.AddRelativeForce(Vector3.forward * 100, ForceMode.Acceleration );

based on the computing power of the computer the game in runing on the Game object will move faster or slower based on the frame rate or time of the game. I would like to know what I can do to make it so even thou the frame rate is less or higher the GameObject will always move at the same velocity.I would really appreciate if someone can help with this. all the information out there is very contradicting some people say is ok to multiply force by Time and some say that’s not a good thing to do let me know what you think.

For moving rigid bodies you should be adding force in FixedUpdate(), and then multiplying the force by Time.fixedDeltaTime.