How to submit form value on .env or config/myconfig.php?

I have a CRM for menaging data, so far so good. I am thinking to add some seetings extra option on my CRM, i am thinking for a route /seeting-value and on this to display a form. I mean when a user go to this route to personalize CRM as his like, for example site-name, body-background-color, site-description, maybe to change db config. I know this config have to do with .env and config/myconfig.php , what i dont know is how to pass this submit form on emv or my config, how it really works. I have search on google but i didnt find any good documentation about this. Any one have an idea?