Leon may complete a slew of Requests in Resident Evil 4 Remake to earn Spinels from the Merchant. Since there are occasions in the game where you may not be able to return to earlier places, it is recommended that you complete the side missions as quickly as possible after receiving them.
Resident Evil 4 Remake: Grave Robber Request Guide
In Chapter 3, you'll be able to enter the church for the first time. Although it's recommended to do this quest immediately, you'll still have opportunities to do so in subsequent chapters.
In the middle of the cemetery, a grave marker for the pair has been placed. Both are marked with a V. A dead tree and a rusted-out fence are also notable landmarks.
The emblemia is easily broken, so all you need to do is draw your revolver and fire or slash at the icons. You have completed the required task and may now return to the previous region to collect your prize of two Spinels from the Merchant.