Install BulkOps from the Atlassian Marketplace into your Jira Cloud site. Only a Jira admin can install apps.
After install, BulkOps is available to anyone in your site who can see Jira issues — every action runs with the acting user's permissions, so users can only do what they're already allowed to do in Jira.

Open BulkOps from the Apps menu in the issue navigator

BulkOps operation panel before selecting an operation

Successful run shows succeeded/failed counts
Tip: If you select issues with checkboxes before opening BulkOps, the operation runs only on those. Otherwise it runs on every issue matching the current JQL.
If you find yourself running the same operation again and again — for example, Add label triaged and reassign to the team lead — open Apps → BulkOps Presets and save it as a preset. You can then re-run it with one click from the issue navigator.
Want a preset to run every day automatically? From the admin page, attach a JQL query to a preset and it will run on a daily schedule against whatever issues match at that time.