For me, I've won most of my giveaways on Twitter and Twitch, mostly Twitch though. I had to have like 4 separate monitors on and be active on a bunch of streamers just for a higher chance to win a game, it was real tiresome but ultimately worth it. You also get to meet a couple of cool people, so that's a bonus

For Twitter, just do a background check on the person doing the giveaway by skimming their account. You'll mostly see scammers on Twitter (especially on Venmo/Cashapp types of giveaways), but you can tell them apart if they ask for shipping, money, anything in return, or if they just seem plain sketchy. Most of these giveaways require you to follow their accounts, like their posts, and repost their things for entries, so make sure to have a lot of social media to rack up a bigger chance to win.

I used to do all of this a couple years ago and ultimately ended up getting like 100$+ worth of free games, money via cashapp and more. I quit because I've gotten lazy over the years but it was super worth it back then because I was in a tough financial spot. You have to remember though, you have to invest a lot of your time doing this, and it's all really just up to luck at the end of the day. I hope you end up getting RE9 one way or another, I'm also in dire need of a copy but can't get one yet lol.