How we can Change the version of Datebase?

Respected Members, I'm newbie at OVHCloud Community so May be it is irrelevant question,

I have several shared hosting that host sites Like Jazz Daily Internet Package that I want to take over largely. In order to reconsider their sustainability I wanted to reassemble the php (easy) version and do the same for the bdd version.
I can't find how to do the database, can you direct me please? (or tell me it's not possible : open_mouth:)

thanks in advance