No, as IPv6 does not work that way.
The Long Read
While IPv6 does carry several changes and enhancements/simplifications of protocol handling, none of them are about latency. It's main feature is an increased address size to 128 bit. That's more than enough to give each possible planet in the visible universe a dedicated address range the size of the IPv4 network (*1). More so right now only 1/8th of this range can be used at all.
More important here is that segmentation of IPv6 does not of the same hard structured kind as with IPv4. Block allocation is way more dynamic and 'rightsized'. There is no need to give 'territorial' addresses but rather provider orientated, so feel free to open one or multiple providers on the moon (*2).
What it does not solve are basic interplanetary communication issues. Store and forward systems like mail - or basically anything batch (file transfer) orientated (*3) - will work fine and at line speed (*4), even over interplanetary distances. But any kind of interactive services that requires genuine user input will suffer full round trip time, no matter what protocol (*5).
*1 - Back of an envelope calculation:
- There are about 10^78 atoms in the visible universe.
- 10^25 atoms are roughly in a kg of matter
- Earth got about 6*10^24 kg, so lets use 10^25
- This gives us enough matter for 10^(78-25-25) or 10^28 planets.
- An IPv6 address is 128 bit,
- IPv4 is 32 bit,
- leaving 2^96 IPv4 sized networks (or names) for planets.
- 2^96 is 8*10^28
And yes, like any such estimation there are many arguments to push it a few magnitudes to either side - like that only a rather small amount of matter would exist in form of planets - still, 2^128 is a pretty big number way past anything mankind needs ... then again, we are known to be rather wasteful, so I'd better hedge my bets :))
*2 - For world building this means provider wars and great firewalls do work on the moon as well :)
*3 - This includes any database like news aggregation or, well, Wikipedia. Of course, concurrent edited databases experience way more colliding edits, but will work quite fine in reading mode. I expect any future manned spacecraft and colony to have read only copies of Wikipedia maintained by continuous update service. And at some point (world building) a bad mood about cultural domination by Earth :)
*4 - Simply by using (much) larger packet windows (local buffer memory isn't expensive in such a setting), as well as multiple hops each doing store and forward.
*5 - One my envision some kind of 'user support' AI that returns possible answers, before the full request has been received. Of course that only works with requests that includes a lot of data, providing a chance to answer ahead of receiving the full request.
Similar when a request results in multiple answers, they could be sent interleaved and in a refining way. Much like sending first a low resolution image and then adding to it, so a decision how to proceed can be taken early on. Much like (good) web pages are made to work well on slow connections.