Yes, you can coach

The most common reason people decline to coach a technical lead is that they do not feel senior enough. It is worth examining, because the thing that makes the conversation work is not seniority.

What independence buys

A coach who has no vested interest in what the lead decides can ask the question that the lead's manager, their peers and their reports all have a reason not to ask. That is the whole of the leverage. Nobody inside the situation can offer it, however experienced they are, because everybody inside the situation has a stake in the answer.

What you do not need

1. You do not need to have held a larger role than the person you are coaching.
2. You do not need to understand their systems; if the architecture is genuinely the issue, that is a review, not a coaching session.
3. You do not need answers. The failure mode of experienced coaches is having too many.

What you do need

The ability to sit with a silence, the discipline to ask rather than tell, and enough structure to keep an hour from wandering. Those are practices, and they improve with repetition much faster than most people expect.

Starting

Read the model and the mechanics, agree a short series with one person, and ask for feedback at the end of every session. Three sessions in, you will be materially better at it than you were before you began.