How do you establish yourself as a potential mentor for your direct reports and junior staff when you’re new in a leadership role?

When you are new in a leadership role, becoming a mentor does not happen overnight. It starts first with building trust. For me, it was 2 important things - 1. Being genuine to them 2. Just showing up consistently and being there for them.
I never skip 1:1s. I always dedicate the first 5 minutes for individual well-being. We also talk about what’s going well, where they are feeling stuck and how I can support them better. After that, we shift to career goals and what they are learning or want to learn more. These small but regular things have helped me connect with them beyond just tasks.
I also make it a point to jump in during high-pressure production issues. Not to take over, but to show that I am right there with them, contributing technically and backing them up when it matters most. And every month, I call out great work publicly through our company channels.
All of this has helped me earn their trust and build the kind of relationships where mentorship happens naturally based on support and shared growth.

Establishing yourself as a mentor as a new leader:

Firstly make sure that people know you are open to being a mentor - it takes time and energy and not everyone will feel its OK to ask.
Demonstrate your capability - walk the walk so to speak - this will establish your skills and credibility
Be a good listener - you have to be approachable, able to listen and ask questions, not just immediately move to advise mode.  This will build trust.
Repeat these behaviours to demostrate your consistency in these things - especially as a new leader; you're an unknown quantity to your team and you can't force that.

1. Notice people – listen to them first and don't talk too much. Just listen to what they expect and who they are.
2. Talk to them - and show them who you are and what your values are.
3. Build trust and show them who you are - this is the most important thing, but it is not possible to achieve without steps 1 and 2, or without being authentic, organised, disciplined and keeping your promises.
4. Build strengthening relationships with them and be empathetic.

Now you can become a mentor.

I can't understate the importance of learning from experts.  There are many fine leadership books, but some are better than others.  I've found both books by L. David Marquet to be outstanding aides in framing leadership responsibilities.    My recommended top 4 are:
* Leadership is Language (L. David Marquet)
* Radical Candor
* The Speed of Trust
* Crucial Conversations

Secondly, you need to decide what kind of leader you want to be.  Some leaders are bullish and prize control, respect, and authority.  Others take a more nuanced, people-first approach.    There's not a one-size-fits-all approach.  

The example books I listed above fit my leadership style, which is one of servant-leadership.  A mentor should above all be wanting the person to succeed in their own merits.  This means helping them learn key skills, not dictating solutions to them.  

Establish shared values with your directs, this will help frame mentor model.  

Finally, mentorship implies some degree of expertise in the subject matter.  If you are new to leadership, start by listening to what people are telling you, and be honest/open with them.  Explain that you want to be a better leader, and that their feedback to your style is important.  As you get this feedback, apply it, grow, and then you'll be the mentor you want to be.  Good luck!