How to add transition for background image scaling up on hover?

So what I’m currently trying to do is have the background image of a button on my home page scale up, without affecting the size of the rest of the button.

As you can see in the read only, I have the first button now so that it has the ideal effect I’m looking for when you hover over it. However, obviously I need to smooth out the effect.

I took a look under transitions but didn’t see any property which matches what I’m trying to do here.

If anyone know how to add that transition effect, or if I need to accomplish this is a completely roundabout way, I’d appreciate you letting me know! Thank you!

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