Here you will find not so much ready-made circuits as an explanation of what works and why it works that way. And what to do to make the circuit work the way you want it to.
Many electronic circuit books are called “cookbooks”. That’s because they just have circuits drawn on them. That’s all. And how they work, what properties they have – they write about this very briefly. As for more complicated questions, for example if it is possible to change power voltage or gain, you will not find any answers at all. It is the same with the schemes on the Internet.
And how many good meals have been ruined because of a typo in the cookbook!
If you only need one scheme once in your life, use the cookbook. If you want to understand exactly what you’re doing, how it works, and what to do to adapt the scheme to your tasks, or even improve it, then this is the place to go!