Here's a marvelous example I've stumbled upon yesterday: https://juro.com/policy.html

The entire privacy policy is very well done (and beautifully designed, I may add). Clear options, transparency over who gets your data, ability to use the product without providing PII and all sorts of other goodies.

Specific quotes related to consent:

> If you have previously given consent to our processing your data you can freely withdraw such consent at any time. You can do this by emailing us at support@juro.com. If you do withdraw your consent, and if we do not have another legal basis for processing your information, then we will stop processing your personal data.

Disclaimer: I'm not affiliated with Juno nor am I their user. I just randomly stumbled upon their privacy policy.