✔ 最佳答案
"could make" is the main verb of the noun clause (object of 'found").
There is no 省略 after "laughs".
The structure of this complex sentence:
(0) They found (1) [noun clause].
(1) that + [subject] + [verb] + [object] + [object complement]
[subject] = the way + (that) a person laughs
= (how a person laughs)
[verb] = could make [incomplete transitive verb, i.e. need complement to complete a full meaning]
[object] = one [pronoun]
[object complement] = [adjective phrase] more or less attractive to others.
more or less = [adverb phrase] modifying 'attractive"
attractive = [adjective]
to others = [prepositional phrase] as complement of "attractive"