This guide will let you know how to get through the Silph Building in the Let’s Go Pikachu & Eevee. You have to follow the steps in this guide to get the free Lapras from there.
After getting into the elevator, you need to go to the 5th floor. The Silph Building is occupied by Team Rocket in Saffron city. You have to fight there to get a pass or key to open the doors. You need it to get to the top of the Silph Building and fight with the Archer. He will run after getting defeated by you. After getting the key from him, you need to go to the 7th floor.
You can get the free Lapras from there. You have to talk to the guy who sits inside the room, and you will get it.
Now you need to go to the 3rd Floor. You need a key to get to the 3rd Floor. After getting to the floor, you have to come to the room where you can teleport yourself.
Then you will come to the top floor by teleporting yourself. There is the boss in the room, and you have to fight with the boss.