My wife had the same thoughts. She said men do not like bigger women, and she lacked self-esteem,
saying I was biased, as her husband.
I introduced her to some forums where she could chat and read messages from other men, and see men liked bigger women.
We made some anonymous photos, and posted them with a burner account, and she got a lot of hot comments, and more.
She also got a lot of propositions, and a lot of cock photos, which she was not enthusiastic about at first,
but warmed up to that, after she chatted with some of the more intelligent guys, and eventually did live chat with a few later.
It helped her self-esteem a lot, to chat with younger men, and see them excited to see her nearly naked, even masturbating together.
From there, that's how we got on the route to hot-wife/cuckold relationship.