GTA 5 is free on epicgames.com. There's a bunch of them that are free like Paladin and Magic The Gathering...
Those other games are "Free to Play", i.e. the base game is always free (like TF2).
You can't claim a free game on your account without enabling 2FA. It's a scheme perpetuated by the Chinese/Tencent to collect your phone number.
Phone number is probably only needed for SMS auth. E-mail is required for all 2FA methods they offer though.