Ragnarok preorders are available now available in the UK across all the retailers. However, India doesn't seem to have any retailer that will provide God Of War: Ragnarok Collector's Edition.
In the UK, the God Of War Ragnarok collector's edition is exclusive to the game. Preorders are also expected to go live via PlayStation soon.
In the UK, the God Of War Ragnarok Jotnar edition is exclusive to the game. Preorders are also expected to go live via PlayStation direct soon.
If you purchased the Ragnarok standard edition for PlayStation 4, you can easily upgrade to PlayStation 5 version for $10 only (or equivalent currency)
When you buy Ragnarok launch Edition you can get two cosmetic skins; the Kratos Risen Snow Armer and the Atreus Risen Snow Tunic