New multisite for subfolders

Hi there, I have worked with multisites before, but for multi domains.
Now I have a new WP at:

https://esourcecapital.com/gapps/

Turned it into a network, added a new site:

https://esourcecapital.com/gapps/en/

But I want the main site to be at:

https://esourcecapital.com/gapps/es/

How do I move the main / to /es/ ?
Is it a database parameter or is it the:
`define(‘PATH_CURRENT_SITE’, ‘/gapps/’);

At wp-config.php?