Go to language and region > click 3 dots for your language > language options > add a keyboard > add Dvorak (or whatever). Then either remove the qwerty layout or do win+space to actually select the keyboard layout.
Win + spacebar doesn't work in some cases and if something is opened in fullscreen, closing it isn't very convenient. The actual key binding that works is alt + shift I think.
Technically alt + shift changes between languages and ctrl + shift changes between layouts within the current language. Win + spacebar circles through all of them. So if you want to change from qwerty to dvorak I don't think alt + shift will work, at least in windows 10.
I absolutely hate that there are 3 ways to change my keyboard layouts. I very often hit control shift and since it's hidden that the layout was changed I wonder why the last sentence I wrote is gibberish...