There are only a few IPv6 public DNS servers for worldwide/global services currently (Not as many as IPv4 public DNS resolvers).

Cloudflare:

• 2606:4700:4700::1111
• 2606:4700:4700::1001

Google Public DNS :

• 2001:4860:4860::8888
• 2001:4860:4860::8844

OpenDNS:

• 2620:0:ccc::2
• 2620:0:ccd::2

Quad9:

• 2620:fe::fe
• 2620:fe::9

CleanBrowsing:

• 2a0d:2a00:1::2
• 2a0d:2a00:2::2

Neustar:

• 2610:a1:1018::5
• 2610:a1:1019::5

OpenNIC (http://servers.opennicproject.org / http://servers.opennicproject.org/?tier=2):

• 2001:470:f032:10:0:100:53:10
• 2001:470:8269::53
• 2a01:4f8:101:3062::5:2

You can visited: https://www.opennicproject.org/nearest-servers/ to get the closest OpenNIC DNS servers.

Yandex.DNS:

• 2a02:6b8::feed:0ff
• 2a02:6b8:0:1::feed:0ff

You are welcome to comment more :)