How do I change the canvas size of my Previous GAME?

i want to resize my previous game which made in 1260,720 canvas size

now i want to resize that game into 480,320 canvas size so how can i do this

In the Properties panel click 'view' on Project Properties, then enter the new resolution in the viewport size section. Depending on your game you may then want to change the layout sizes for your layouts.

After doing this, you will need to resize all of your art assets to match the new viewport size.

thanks for the answer

but how can i know which size of assets is match to my new layout size

Is there any trick for it?