Path of Exile 2, being an extension of Path of Exile 1, won’t have separate cosmetics. Here’s what you need to know:
Shared cosmetics across Path of Exile 1 and 2: Any cosmetic microtransactions you’ve purchased for Path of Exile will be usable in Path of Exile 2, with some exceptions. Grinding Gear Games, the developer, confirmed this during ExileCon 2019. Their reasoning is that both games are built on a shared platform. This means you can use all your existing armor sets, weapon effects, skill effects, and other cosmetic items in both games.
Exceptions for Path of Exile 2 cosmetics: The exception applies to cosmetics that are hyper-specific to the content of one game. For instance, since Path of Exile 1 doesn’t have a bear form transformation, a microtransaction that reskins your character into a bear in Path of Exile 2 wouldn’t be usable in Path of Exile 1.
Overall, you can expect a vast library of cosmetics to customize your character in Path of Exile 2. Keep in mind that new cosmetics will likely be released alongside Path of Exile 2, and these may not be usable in Path of Exile 1.