Question Canvas Scaler Reference Resolution for portrait mobile

If I'm designing a game exclusively for mobile in portrait, should I reverse the Reference Resolution X and Y on my Canvas' Canvas Scaler component (1080x1920 instead of 1920x1080)? Does it not particularly matter? I've played around with both and can get everything to scale nicely regardless of resolution or aspect ratio, and both look fine when changing devices in the simulator. How it specifically affects things just isn't clicking for me. Could anyone provide a bit more clarity?

I've searched around and haven't been able to find an answer to this specific question, but this post was very helpful if anyone is curious and looking for more info around this.

edit: Unity Legacy documentation has this to say:
"In our case, we set the Canvas Scaler to be the Phone HD landscape resolution of 640 x 960. Now, when setting the screen resolution to the Phone SD portrait resolution of 320 x 480, the entire layout is scaled down so it appears proportionally the same as in full resolution."

I think this means I should be setting my Canvas Scalers to match the intended screen dimensions, but I would still appreciate any clarification.