Is it a way to call a theme or a language with url? I am working on a new theme but it would be really easier if i could test the theme with a url string to check if its working other than set it from admin to avoid logging in and out every time i made a change to test. This theme i hope to let the client change their language from the header of every page so they can make changes directly if like to.
No, at least not without altering the code which loads the theme. Why don't you install a VM and set it to your theme for development?
And you do not have to log out and in again when you make a change in your theme during development. You must just do that when you switch to a different theme.
Sure but if something fails until its fully functional i cant access admin site thats why i hoped it was possible. But is it any theme development documentation available ?