The ExpCreator plugin allows you to customize the experience of any block in Minecraft. You can assign experience accrual for mining any block in Minecraft. For example, you can assign 5 experience points for mining a stone.
If you set your experience value via the plugin, then it will become a constant. In this case, for each extracted coal, you will get exactly the number of experience that you specified in the config.
This is config.yml:
GRASS: amount: 1 STONE: amount: 5 CHEST: amount: 11
The config shows that you will get 1 experience for mining a block of grass. For extraction of a stone – 5 experience. And for the chest – 11 experience. You can remove these values and add your own, there are no restrictions. The main thing is to write the correct names of blocks from Minecraft.