If you are doing "Agile" you should have a regular meeting with your team, to discuss improvements to how you do your jobs and how you perform. If you are doing Scrum this is called the Retrospective, but you can have a different Agile implementation and a different name. But that is the meeting to discuss all your work related objectives. Your manager should be one level above that and not really in on the intricate details of how your team does its job.
I said should. If that is not the case, you are not doing "Agile". There is no agility without inspection and adaption. I have no real advice for you if you don't do that, because your question loses all its context. It would be like asking "How to be a good driver? We race Formula 1, just not with engines in the cars". Even the most seasoned racecar driver would be like "uh, what? I don't even know where to start here...".
That said, what is the 1:1 about? What can and should you bring up?
Well, all the nitty gritty details of work have already been covered in your other meeting. The 1:1 with your manager is about problems you cannot solve in your team. Or have been "solved" in your team in a way that doesn't make you happy, but could be solved differently on a higher level.
What that would be is up for you to find out; we don't know your company or situation. Anything actionable, that your manager can fix or bring to attention of higher-ups to fix. Anything you need to personally improve outside of your team.
Two tips on what makes managers' (and by extension yours, too) days better:
Don't use your manager as a "power up" to counter team decisions. Your team is supposed to work and come to agreements on their own in an agile setting; if everyone that isn't happy with team decisions complains to the manager, that is not only non-constructive, but the manager will be frustrated, because they should not interfere with team decisions, so this is a lose/lose conversation for them.
Positive reinforcement. If your manager did something you liked, let them know. If you told them about a problem and they fixed it, let them know it's fixed to your satisfaction. If they hired someone you think is really good, let them know they made a good decision. Talk about positive things, too. It is really nice to hear about positive things in a day full of 1:1s as a manager.
You got 30 minutes. There is no need to fill those 30 minutes with something. If your topics cover 20 minutes, great. Done. Don't drag it on. Everybody likes a clean message and an additional break. It also underscores your sincerity once you have a topic that is important to you and takes the full 30 minutes.
If you get noticed as the guy that mostly says something positive or solves their problems in the team, you will not only leave a positive impression, you also get more impact with the points you do have to make once in a while. On the other hand, if you use the 30 minutes to complain about stuff for 30 minutes, it will just be "same same" if you bring up a topic that is really important to you. Pick your battles.
You asked what "high performers" bring up in those meetings. Last time I had them, I considered myself a high performer in a team of mostly high performers. Other teams under the same manager were staffed differently. One thing I found positive about our team was that we found solutions to things that were work related. And we respected team decisions. So most of the time, I really had nothing to discuss. We solved issues in the team every two weeks and we had a Scrum Master that would bring anything to higher management we could not solve in our team alone. So there really weren't many issues for me personally that weren't already handled in a different path.
There were courses and certificates I wanted to take, and that came out of the manager's budget, not the team's. So we talked about that.
Then there were mandatory yearly trainings, where I suggested we could maybe take the test first and be spared from the 2 hour boring training, if we scored 100% anyway. So we talked about that.
We talked about my trainees a bit, but since the supervising authority for them was HR, it was just a rough outline to keep my manager informed.
I think that's it. Otherwise, it was a lot of "Hi, how are you, got anything new? No? Me neither. Nice to see you." You don't need to fill the 30 minutes.