You should be able to do that with Automation For Jira. If you are using Jira Cloud:
Now when each issue is created, it will add the desired default label as long as the issue is created in that project. You might need to refresh the page after each issue creation to see it.
You can do this via global rules to apply to all projects also. You'll need to be a Jira Admin/Site Admin, then instead of going to Project Settings, go to Jira Settings (cog icon on left-hand navigation bar) > System > Automation Rules (left-hand menu).
For more on using Automation For Jira see these help pages.
Hello Community! I hope you've been enjoying the 🍂Apptoberfestivities🍂 (I know I have!) The event is heating up next week with a series of virtual events that we're calling the 🍻🍂Partner App ...
Connect with like-minded Atlassian users at free events near you!Find an event
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no Community Events near you at the moment.Host an event
You're one step closer to meeting fellow Atlassian users at your local event. Learn more about Community Events