The safest way to experience the game at no cost is to play locally on a friend’s computer during a LAN party or gaming session. Phasmophobia supports local co-op on the same machine (though each player needs a separate Steam account and copy for online multiplayer).
Steam allows gifting. If you have a friend or family member who already owns Phasmophobia, they can purchase a second copy as a gift for you during a sale. Offer to trade a game of equal value from your library. Free Steam Account With Phasmophobia
Steam does have a legitimate feature called Family Sharing, which allows a friend or family member to play your library on their device. However, this requires the owner to authorize your device. Publicly distributed "free accounts" claiming to use this feature usually violate Steam's Terms of Service. Furthermore, if the owner is playing a different game on their library, you will be kicked off. The safest way to experience the game at