User data, beginner's question

hello, I would like a suggestion, I’m thinking of creating an app for the user, I’ve already made an app but never sent it to google play.
I would like to know how the database would look for several users who download the application, I only worked with spreadsheets and I believe that it is not possible to do the same without access permission.
So what would be best for users to store their data?

for local databases try TinyDB or SQlite