Resident Evil 3 Remake has some safes that will give you various useful items if you manage to open them. To do this, you will need to find a safe code. The first safe you will find in the game is the one near the drugstore. The exact location of this safe is shown on the map below.
To get the safe code, you will need to make your way to the drugstore. There are two potential routes, but the easiest way is to head to the back of the room with the safe and go through the door. Turn right and go the end of the hall, then leave through the door in front of you, and you will find yourself on a fire escape. The pharmacy is directly across the street.
There is one zombie in the back, so be careful. Take it out, then grab the herb at the counter, and the gunpowder on the shelf, then head to the back of the building and look at the Aqua Cure posted on the wall. There will be three digits on it that are highlighted, and this is the safe code.
Now, cross the street and go up the fire escape, then in the door. Be careful, as there is another zombie that can show up here. Take him out and head deeper into the room and back the safe. Use the combination you found on the poster to open it and get the Red Dot Sight.
So far, the combinations we know are any of the following, but it will be random for your playthrough, so it is best to check the poster first, before heading to the safe, or you can try all three below:
The combinations are always Left, Right, Left on the radial locks on the safes. When you manage to get this safe open, you will get a Red Dot Sight upgrade for your handgun.