The evidence says: far less than your feed does. At 24, exactly one intervention has randomized-trial support for preventing visible skin aging, and it's the least glamorous one — daily sunscreen. In the Nambour trial, adults randomized to daily sunscreen use showed 24% less skin aging over 4.5 years than the use-it-when-you-feel-like-it group (https://pubmed.ncbi.nlm.nih.gov/23732711/). Sun exposure drives the majority of what people read as facial aging, so consistent SPF in your 20s is the highest-yield decision available to you, by a wide margin.
The next evidence tier is retinoids — the most-studied topical anti-ager, with trial support for improving photoaging once it exists (https://pubmed.ncbi.nlm.nih.gov/3336176/). Starting one in your 20s is reasonable if you want to; it is not an emergency, and "never started retinol at 24" is not a fate.
Everything past those two — essences, peptide stacks, ten steps — is optional. Some of it is pleasant and hydrating; none of it carries prevention evidence remotely comparable. More products mainly buys more chances at irritation (https://www.aad.org/news/dermatologist-guide-skincare). As for "preventative" injectables at 24: that's a cosmetic choice with a plausible logic for expression lines, not an evidence-backed necessity, and no one should let a comment section prescribe it.
So: sunscreen every morning, moisturizer, retinoid if and when you feel like it, and the confidence to scroll past the rest. Boring, cheap, and better supported than the arsenal.