Wandering through to mention that your local library almost certainly has a collection of cookbooks spanning decades, and, depending on your area, might even have stuff tied specifically to your region. Take the book, photocopy the recipes you're interested in, return it, get to cooking!

America’s Test Kitchen. All you need. Recipes for nerds.

I have a cookbook (not a recipe book - there's a difference) from 50 years ago (with the latest edition being 2019) and it's amazing. No need to go for modern hipster recipes that don't teach you anything...

my mother has something like 8000 cookbooks she's collected from the 1930s to around 2015.

I think I'm set.

Wayyy ahead of you, I have a collection of vintage cookbooks that is growing by the day! Muahahahha :D

As someone who lives at an altitude above 50ft, most cookbooks always kinda sucked out-of-the-box.