SharePoint Migration Tool

Ajay Mandal if you have Azure AD Connect deployed in your environment and all users are synced to Azure AD , then the tool will automatically map the on-prmise user SID to the AAD Upn.  if thei is not the case then you can create a mapping of the users SID to UPN  and then migrate. Check this. https://docs.microsoft.com/en-us/sharepointmigration/create-a-user-mapping-file-for-data-content-migration

for the Created Date and Last Modified Date. They too are migrated.  it takes the NTFS file attribute and updates it to SharePoint Online