Yes. The official FAQ says the core game can be enjoyed without in-app purchases. Paid currency, add-on content and optional editions also exist; free to play does not mean that every item is free.
The base game is free
The Epic Games Store FAQ explicitly states that in-app purchases are not required for the core gameplay experience. Console listings also describe a free base game. You do not need to treat a highlighted preorder edition as the admission price.
What are the paid editions?
As of September 13, the Advanced preorder pack was listed at $9.99 and the Collector’s edition at $19.99. These are optional additions. Prices, availability and included content can vary by store and region.
Read each edition’s contents before buying. The PS5 Advanced Companion Handbook description includes a Prismana egg and evolution materials, so paid content includes more than cosmetics.
Currency, extra content and subscriptions
The official FAQ confirms that in-game currency and add-on content can be purchased. Check the in-game shop for item prices and any probabilities before purchasing.
Platform subscriptions are a separate question from the game’s price. Check the requirements displayed by your console store for the specific multiplayer experience you want; a general storefront subscription notice alone is not a complete answer.
Based on the official information and attributed reporting below. Store availability and launch details may change.