Decide on authorship and order BEFORE you begin writing (preferably early in your research process).
Contributors: Examples of activities that alone (without other contributions) do not qualify a contributor for authorship are
For a full list of Contributor roles, see the CRediT website.
What about AI?
Authors who use AI should describe in the cover letter and submitted work how they used it. Chatbots should not be listed as authors because they cannot be responsible for accuracy, integrity and originality of the work (required for authorship). ICMJE IIA4.
Breaking up research in order to get several publications is often called "salami slicing" or "data fragmentation" or "least publishable units." Don't do this!
Elsevier. Salami slicing