The beauty of AzureDevOps is you can add your own states to AzureDevOps without modifying the templates

Here let us see about how to add new states to a Agile template in AzureDevOps

pre-requisite: You should be one of the Administrators of the organization to edit Process templates

Step 1: Go to Organization Settings —> Process

Step 2: Click on Process template on which you want to modify the states

Step 3: Click on the WorkItem Type you want to add the states (Bug or UserStory etc.,)

Step 4: Once you click on the WorkItem type say “Bug” you will get the process template displayed as seen below

Step 5: Click on the States

Step 6: Click on “New” and Enter the state name as show and then Click on “Create”

Step 7: Once you click on “Create” your customized state will be displayed in the list of states

Step 8: You can also see the states in the “Bug” itself as shown

And you can also go through

Hiding any state in Azure DevOps
Deleting a state in Azure DevOps
Editing & Renaming states in Azure DevOps
Adding new states in Azure DevOps
Removing Closed state in Azure DevOps