In an organization that doesn't have a defined career path for engineers (which is to say, most organizations), you need to take responsibility for yourself if you want it. If you're on a team of engineers and nobody is leading, then step up.

Help newer engineers learn skills, help interview people, help run meetings, and instigate new projects. Cook up a new product or feature, and champion it. If it goes well, you'll be the de-facto tech lead.

Of course, you might just be at a very flat organization where nobody reports to an engineer. In many companies there is no formal idea of a tech lead - you report to somebody who used to be an engineer, but is now a manager.