I think there are probably almost as many definitions of tech lead as there are companies. In my case the tech leads in the company are responsible for turning high level requirements from the rest of the company into actual actionable work, and feeding back up to senior management places where we could improve the existing product by refactoring/introducing new features. Alongside that we do line management for the people on our team, and generally act as a point of contact to try and reduce the level of interruptions to developers.

It’s very much not an IC role - we might throw together the odd prototype, and we’re all very capable of rolling our sleeves up and helping out if a project needs an extra person for a bit, but the general rule is that if we’re on the critical path for implementing a project something has gone wrong.