How do I make an item that when right clicked it has a chance to give you another item

Go to the "Triggers" tab on your item's settings.

Create a new procedure and set it to trigger "When right-clicked."

Inside the procedure, do the following:

Generate a random number between 0 and 1 (this will act as the probability check).

Compare this number to a chosen threshold. For example, if you set the threshold to 0.7, then any number below 0.7 (70% of the time) will result in the player receiving an item.

Adjust this threshold to control the drop chance. (example: 0.1 is a 10% chance, 0.2 is a 20% chance, 0.3 is a 30% chance... and so on)

https://imgur.com/gallery/procedure-wlf79T5