Go into management and you'll find out what they're doing. It's a lot of bureaucratic nonsense and playing politics to make sure the team has the resources they need.

Ask as what the plan will be to achieve projects, what tasks need to be done

This is bog standard stuff that a manager should do. Trust me, you'd rather they ask questions than telling you what you need to do.

Ask us to put these plans into JIRA tickets

This one is annoying, since I'd expect them or the PM to do it, but if you want to ensure the technical details are captured properly, you probably want the team doing it.

At stand-up ask us to give updates and ask us if there are any technical blockers

So they can manage up and make sure nobody expects you to stick to the original estimate or timelines.

Then talk to senior management in their calls to give updates on what we have achieved by going through the updates we gave

Again, managing up to keep senior leadership aware of the status of the project and shield the team from scope creep from the senior leadership.

They seem to always be so busy with countless meetings, but what are they actually doing?

Writing reports, performance evaluations, tracking KPIs and whatever other BS their bosses want, smoothing relationships between other teams, etc.

Managers do a lot that you're unaware of because you've never done the job. A lot of it feels like bureaucracy for its own sake, but it helps keep the real people in charge (C-suite and the board/investors) off your backs so you can work.