On this topic, I have to recommend Hush! It is an excellent free, open-source and well-maintained app for iOS.

https://oblador.github.io/hush/

iOS Safari 18.5, installed and enabled in both normal and private modes.

Opened a private tab and navigated to youtube.com - got cookie consent regardless.

Closed every app, restarted safari fully - same results. Same on google maps.

Uninstalled.