Company-managed (classic) projects
To show dynamic fields on the issue view in company-managed Jira projects, simply add them to the respective screen of your project and issue-type:
Team-managed (next-gen) projects
For team-manged Jira projects, you first need to enable Dynamic Custom Fields for Jira for each project where you’d like to use dynamic fields on the issue view. Navigate to Project Settings -> Apps -> App fields and enable “Dynamic Fields for Jira”:
Once you’ve enabled the app for your team-managed project, you can simply add dynamic fields by adding them to your issue types:
There’s currently an open Jira bug that prevents newly created dynamic custom fields to be displayed in this list.
Please disable and then re-enable “App fields” for “Dynamic Custom Fields for Jira” (first screenshot) for newly added fields to appear for team-managed projects.