Depends - sometimes with simple Jira boards, sometimes with other tools like Smartsheets or Air Table or a simple spreadsheet, sometimes with post-its and a white board, sometimes with no system formal or otherwise. My point is less about Jira specifically and more about tool/process dogma (although I do think Jira is the tool of choice for most “we must used the Agile Toolkit Scaled Enterprise Framework Productivity System MegaProcess for all things!” types than others, mostly because of having been around forever and because of Atlassian pitching organizations to use Jira workflows for compliance as if it were uniquely capable of tracking when someone clicked a button in a UI).

One way is for senior engineers to give junior folks well-defined areas of responsibility, and then not worry about assigning and tracking small tasks within that. The more senior folks explain and motivate what we need and talk through what the interfaces around the area are and how it fits into the broader work of the team, then help as-needed.

Instead of trying to "track" work in terms of tasks, you keep up with the state of the system by understanding the state of each area. Which is pretty natural to do since you'd be helping with design discussions, code review and some pair programming and debugging.

You can get a lot done by talking and by looking.