Half the fun of Resident Evil 3 is running through the story multiple times – not just to earn better ranks and tackle harder difficulties, but also to get some wonderfully overpowered post-game weapons.
Capcom's 2020 remake of Resident Evil 3uses a challenge-based system that incentives you to earn trophies/achievements and score a bunch of kills with all of the standard weaponry, among other goals. The more challenges you finish, the more points you'll have, and the more unlocks you can buy.
That's the gist, anyway. Before I delve into spoilers and talk about this stuff in-depth, I wanted to share a PSA: try to set aside a save file right before you enter the substation. This area is ideal for farming.
If you rushed past the substation and never looked back, no worries – it takes no time at all to reach the area again in a new file. The main trick to know is that you can score quick kills at the substation (and, in turn, wrack up points), then reload your save file to run the farming route again and again.
With that preamble out of the way, let's dive into more specifics.