There is no checklist - each person you ask will tell you a slightly different story. Mine was that I got curious why my company had a poor ratio of managers vs staff level engineers and the occasional questioning of where all the managers came. Others I talked to were pushed into a management position due to dire conditions at the company or former leadership leaving.
My advice if you feel you want to do the move is to learn at how you behave with regards of “Glue Work". I had to do a reflection to understand why I often relied on a manager to do things I could have done myself and later I became sought after on behalf of my team for day to day small issues like: outages, tasks, deadlines, complex deployments and so on. That's part of what is called “Glue Work”. If you are the go to person of your team for some or all of these things, you are a half way there. Look to fix things that are bothering while you are trying to do your work.
Avoid the trap of thinking you are not prepared. It is a paradox: if you are not ready, means you don't know what to do. If you don't know what to do how can you know that you are not ready ? I suggest you read the first part of this post and bear in mind that it is a constant exercise of executing, more than thinking about doing management.
Look at how your company and your current leadership support this move. It may be the case they already have a track and internal recruiting that may give you an opportunity to try your hand on leadership.
On the other hand look for red flags: you are doing a lot of glue work, your leadership is evasive talking about a career move, there is no clear ladder and so on. It may be the case that you have to look around other companies that provide that instead of trying where you are.
The “Tech Lead” role fits well a balance of 50% of time on technical work and 50% glue work. You will find places where you bring what you know and onboard with support of what you should know. You already know how you like to be treated, what worked well in a team and what didn't. That's a great start.
Titles are not always in the hands of your immediate manager as they are tied to compensation, benefits, hierarchy and processes that may not be optimal or open to everyone. Once you are building evidences for this, you have to understand how people are assigned the right role and title.
You will be surprised how many times salary bands, seniority of team members, tenure and other non-actionable indicators are used to promote people internally but are not enforced when hiring. Also look up for fantasy titles vs real titles: Head, Lead, Specialist, Tech Lead and titles without a manager or director word on it may mean different things across companies.
In the next post I'll write about how companies can be ready for people willing to move internally.
As usual, check my book at https://ctofieldguide.com for more content to support your career. Have fun !