For projects…
To look at what other people have done with KiCad, you can find lots of projects all over the Internet, and also when searching directly on source code repository sites like github and gitlab (with the added “kicad” keyword of course) you will find a lot of KiCad related content. Gitlab seems to have an annoying feature that you have to be logged in to even search through the repositories. Gitlab also has a lot of “other KiCad related” content because it the main development of KiCad is hosted there, and other related content such as foorprint repositories and scripts and such.
For example projects you can also have a look at: Made with kicad | KiCad EDA which lists around 50 KiCad projects, and some, such as the Olimex board, have much more extensive repositories with many more KiCad projects.
The “projects” part of Hackaday also has a growing list of KiCad projects.
But those are resources are mostly “just projects”. They can show you how other people have done designs, but they do not show why they have done it in that way.
There are also several PCB reviews here on this forum. Those old threads may be of more value to you because they show beginners mistakes, and have explanations and suggestions to improve the design. The topic below is probably one of the best reviews here. I put quite some time in it back then.
Or do a more generic search on this forum:
https://forum.kicad.info/search?q=pcb%20review