An adjustable composition guide composed of a layer group of vector lines.
A layer group template featuring vector layers making a phi/golden ratio rule of thirds composition guide, which you can drop onto your canvas and resize (make sure the central rectangle matches the same ratio as your final canvas), change the opacity of, and otherwise edit and use however you want :3

After downloading, you can find the material in your downloads, and then you can drop it directly into your canvas and then voila! You can adjust size, the blending mode and opacity however you wish :D
Once you've finished making whatever adjustments you want to fit onto whatever canvas size you adjusted it to fit on, if its a canvas size you use regularly then i recommend saving your new adjusted layer group by going to "Edit -> Register Material", saving it while its the only layers on your canvas, and giving it a name to help you remember what canvas size its meant for, and then you can re-import it into future canvases without fussing around adjusting it!