If you do self host dns make sure you have at least 2 vm's on different subnets (not the same ip ranges) and if you really go smart about it have them hosted in separate cloud providers to mitigate the risk a bit. Then make sure you are aware of how hackers use dns servers for example dns amplification attacks with dns to prevent yours from being used. There is documentation and CIS guides on this. But overall it is not scary. Just a bit of initial admin to get going. As other have mention there is bind, powerdns and that other one that was mentioned Technitium or something (never heard of it before). But as others have mentioned before, Cloudfare really is a good option to selfhost without the infrastructure requirements.