Yes, we can serve multiple domains from an AEM instance.
We need to set up dispatcher accordingly, for domain -> content mapping. For details, please refer to:
https://experienceleague.adobe.com/docs/experience-manager-dispatcher/using/configuring/dispatcher-d...
Other areas might be:
1. Dispatcher: Domain-specific farm, vhost, redirects etc
2. Content aware configurations (if used)
3. Sling Mappings (if used)
Aanchal Sikka