Microtransactions in Hogwarts Legacy are summarized as...
There will be a pre-order deluxe edtion that contains cosmetics and other some non-cosmetics content.
By purchasing this deluxe edition you also gained 3 day early access to the game. During this time public reviews could not be placed for the game.
Many pieces of content, like additional quests or cosmetics, are exclusive to certain platforms and can in no way be obtained on others. Namely PlayStation gets a handful of additional quests.
Other than this there are no microtransactions, DLC, or season passes. There are no announced plans for any of this, but they have not rejected the idea either.