No, I don't buy a game straight away without informing myself first. I always look for all the news and info I can find about an upcoming game, and read any available reviews. I also like to wait a little to see what bugs players have found.
There's only one time I remember purchasing a game for release day, Planet Coaster. There was so much info available prerelease, including lots of info from the beta testing, I felt confident I'm my purchase decision.
When Sims 5 is released, I will likely buy it if it is the type of life simulator I want. But I won't buy until I've done my research. That's just how I roll.