subdomain on multisite : what about ranking?

Hello,

I have this multisite, https://citrotux.org and several subdomains on it: https://projet.citrotux.org
https://projet2017.citrotux.org
https://melodie.citrotux.org
https://meets.citrotux.org

I would like to know if on the tech side I have done right or if I have done wrong on the “possible duplicate issue” point of view, therefore the ranking improvement? This is how it is done:
all my subdomains are done by creating a symlink (done automatically with the graphical user interface in my Gandi.net board).

for exemple could the symlinks be replaced by some code in the .htaccess? If so, how can I do it?

Thanks for your help!

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