Google Stadia has a couple free games (Destiny 2 is one, which can be pretty fun with friends imo), which is great especially if you don't have the hardware/don't have the money to buy new hardware (like me). There are some decent free-to-play MMORPGS (Tera, Guild Wars 2, Neverwinter) if you're looking for those, and I believe FFXIV has a pretty long trial period going on (up to level 30 if I'm not mistaken). I've had some fun with Genshin Impact for mobile RPGs, and Red Dead Online is on sale for $2 right now (you don't need the base game to play). I also tried out Spellbreak (Epic Games and Steam), which is a free-to-play Shooter/Battle Royale hybrid but set in a fantasy world with Zelda:BotW graphics. Pretty fun and interesting, even if the gameplay itself seemed a bit simplistic to me.
Definitely seconding the Xbox Game Pass for $1 deal! It's 3 months for that price, and they have a TON of games you can play either on PC, Xbox, or Android devices (through their cloud software). Since I don't have a ton of money to spare and I'm often unsure if my setup can run a game or not, I love that I can download games and try them out without risk. Outer Worlds, World War Z, Gears 5, Spiritfarer, and Halo have been particularly fun for me. Epic Games also has a free game every single day for the next week and a half, but also gives away free games every week on a regular basis. I've picked up some great ones (GTA V, Pillars of Eternity, and Hitman to name a few).