Yes. I don't recall the details but I think it's required by ICANN. We (Google Registry) support extended Latin and Japanese codebases, and since the registry software that we've written is Free Software, you can see our implementation, e.g. here's extended Latin: https://github.com/google/nomulus/blob/master/java/google/re...
Different TLDs whitelist different code pages/codepoints as allowed under their domains. See e.g. https://www.verisign.com/en_IN/channel-resources/domain-regi... or https://eurid.eu/en/register-a-eu-domain/domain-names-with-s... and the linked https://eurid.eu/media/filer_public/8d/18/8d18473b-ed9b-4fba...