The usual formula for a lead follows a subject, verb, object structure.
The lead has to link to its headline and contain a few elements of the five Ws from journalism (who, what, where, when, why).
At the same time, the lead deliberately leaves some elements of the 5 Ws out to give the reader a reason to carry on reading.
The lead also has to have an insight, fact, or detail that will make a story stand out.
Example from The Sunday Times newspaper:
Headline: 33 Grenfell officers sue for trauma
Lead:
A constable who tried to save a man who jumped from Grenfell Tower is among 33 Metropolitan Police Officers seeking compensation for “psychiatric injuries” suffered after Britain’s worst postwar residential fire.
Unique detail:
Officer trying to save a man who jumped from a burning building.