Change composer vendor folder in composer.json

{
"config": {
"vendor-dir": "../DIFFERENT_PATH/vendor/"
},
"require": {
"phpoffice/phpspreadsheet": "^1.15"
}
}

Composer resources:

https://stackoverflow.com/questions/13353678/use-composer-to-install-bundle-in-custom-directory#answer-27735674

https://getcomposer.org/doc/