Alexandria Ocasio-Cortez graduated in 2011, entered politics in 2018. She actually had more real-world experience than Bill Clinton, by quite a bit (seven years instead of four). Still, she was 29 when first elected. (Not a boomer.)
Nancy Pelosi was 42 when first elected (though she became a member of the DNC when 36). But her father was a politician (Congressman from Maryland), and she helped with his campaigns, so she was literally working in politics from childhood. (She's slightly too old to be a boomer.)
George W. Bush was born in 1946, graduated in 1968. He first ran for office in 1978, ten years after graduation. (He's a boomer.)
Those are just the first four names that came to my mind, though in fairness AOC came to mind precisely because she's so young. Also, Pelosi is from a political family, which I didn't realize, but it often leads to earlier political involvement. Still, it seems that there are NeedMoreTea's point is valid: We've got more politicians who have been politicians for most or all of their professional lives, and less politicians who have been something else for an extended period and then went into politics.
Boris Johnson - Newspaper political opinion straight out of uni, mayor, MP.
David Cameron, Conservative party researcher straight out of uni.
William Hague of course.
Tony Blair was first a candidate a few years out of uni.
Profession of politics does not preclude any backgrounds, though it favors the ones where making connections is the easiest.
They join some party at a young age, and try to get the most privileged position they can.
It's also very common that the only jobs they have before/after their political career, are always in companies that belong to friends, relatives, political allies, or companies that have strong interests in how politics handle some regulations (such as energy companies).
There are of course exceptions, but this is really common.