Here are a couple of ways to automate new users setup tasks via Power Automate Flows rather than e.g. XRMToolbox

Set the timezone

The key is to select the table as usersettingsconfig, via update a row – which will resolve to User Settings. You want to set timezone to e.g. 85 for London. Details here: https://learn.microsoft.com/en-us/power-apps/developer/data-platform/reference/entities/usersettings

Set the user business unit

Via update a row:

Add the user to team

Use relate rows:

Add security roles

Below via relate rows (or unrelate to remove them…)