I'd second that. "Classical companies" are rarely-ever at the forefront of technology, even if they are technology companies themselves.
It's a broad statement, so keep it in context. Examples: Think, Apple has had the iPhone out since 2008 now. Working there on the iPhone 16 HW / SW specs or the M3 processor design may well be cutting-edge stuff, but working there as SRE for the App Store infrastructure is likely "an SRE job with some legacy in it". And working on their developer infrastructure, devtools / CI etc, very very likely is full of "proprietary dead ends" (i.e. tech noone outside the AAPL orchard will use or have use for).
A Wall Street bank, once above a certain size, is going to adopt tech more slowly - much of their proprietary software stack is likely still in C++ / Java where a five-year-old small trading house may have written all that in Rust.
I've had jobs at such "S&P 500" corporates in the past; I wouldn't say "I learned nothing" - I learned how to navigate companies. Call it "coping strategies" if you like. It still helps to get stuff done knowing how-to-do-it on a procedural level - or via human-interaction. Tech-wise ... regretted some of these. My experience, though, is that one can "come back".
"Just" keep the ambition under control that you need to know everything, and need to be able to do everything. Today's "tech stacks" have so many parts in it that are out of your control and that you cannot inspect - the sheer will to "rule them all" will burn you. It's easier said then done, but: know your limits. Everyone has them. You'll recognize the "boasters" soon enough, those that claim they can rule it all.