To be able to use full and wide align, you must run a theme that supports it, this requires the theme to set an option and add some CSS.
Twentynineteen supports this, but if you’re running your own theme you can add support for it yourself. How to do this is written in this article.
Now about the bit of code you sent, setting 'align' => 'full' should be correct and set the default alignment to full. Maybe try recreating your block to see if it’s set to full then?
