newbie image sizes

I am adding QR codes to my videos. QR images seems to generate the same size

I need to scale these images exact same size. but FCP seems to not by like photoshop where there is a
w and h

Is the scale slide the only way to size any jpg or png image on a track? is there a more exact way to scale
dissimilar images to same size? via an width height or x/y field?

You can turn on 'image and wireframe' in the canvas and make the adjustments by hand by clicking on a corner and dragging WITH the shift key held down (so, the opposite to Photoshop). Then, once you have the correct dimensions, use copy - paste attributes on all your other clips, or go to the 'scale' and 'distort' sections to see the numbers you need to replicate the effect.