Of course, just because someone is younger doesn’t mean that they’re a scammer; it’s just something to keep in mind.
Scammers also often list themselves as widowed (especially with a child), self-employed, or working overseas.
The most common reasons that they give for needing money are not being able to afford a passport, visa, other travel documents, or plane tickets (often to come see you); an emergency stay in the hospital that requires a huge sum of money; getting robbed while traveling; or not being able to access their money from abroad.
There’s a huge variety of reasons that you could get.
The profiles of online dating scammers can exhibit some clear signs that something is off—you just need to know what to look for.