GOG Galaxy has the ability to download offline installers. They’re listed under Extras on the game’s page. It’s arguably even better there than on the website because you can download those .bin files all in a single click.

Prime Gaming gives away free games every week or so. It’s one of the perks available to those subscribed to Amazon Prime.

Those games can be on EGS, Amazon’s own launcher (that nobody uses), GOG, or Legacy Games Launcher.

https://gaming.amazon.com/home

Technically, Windows understands both / and \. I personally always use / just because it’s easier to type that.