Stop Killing The Internet: No Digital ID & No Age Verification | European Citizens' Initiative
(citizens-initiative.europa.eu)
Switzerland has implemented laws and a digital system that allows you to verify your age only using a new eID, while promising that it'll be untraceable that your ID was used to make this check and not giving out more info than "yes, this person is 18+". The eID is meant to be optional, but we know how these things usually go.
Whether you trust the promises to be actually implemented correctly and without errors is a different matter. I think it was supposed to be released as open source, but you can't confirm any specific build is actually running on the servers.
So I'd say it's possible and - compared to current "scan your ID" approaches - more privacy protecting. Its implementation is a different matter.