iPhone 8 Plus (Global) / iPhone10,2 latest IPSW firmware file
You can get the latest iPhone 8 Plus IPSW files (iPhone10,2) file from this page. The IPSW firmware file you will get here is pulled directly from the Apple server. This firmware is still being signed by Apple and can therefore be restored with iTunes or 3utools.
This is the iPhone 8 Plus was introduced on the 12th of September 2017. It was made available to preorder on 15th September 2017 and started shipping on 22nd September 2017. The firmware identifiers are iPhone10,2 and iPhone10,5. It's models are D21AP and D211AP for the regular colours and D21AAP and D211AAP for the red models. There are four model numbers, A1864, A1897, A1898 and A1899.
The A1898 iPhone 8 Plus model is exclusively for the Japanese market. It is compatible with FDD-LTE bands 1, 2, 3, 4, 5, 7, 8, 11, 12, 13, 17, 18, 19, 20, 21, 25, 26, 28, 29, 30, and 66 as well as TD-LTE bands 34, 38, 39, 40, 41, and 42. This is one of the iPhone 8 Plus (Global) variants.
The other the A1864 iPhone 8 Plus model is compatible with FDD-LTE bands 1, 2, 3, 4, 5, 7, 8, 12, 13, 17, 18, 19, 20, 25, 26, 28, 29, 30, and 66 as well as TD-LTE bands 34, 38, 39, 40, and 41. It is intended for Verizon, Sprint, and other smaller carriers in the US (but not AT&T or T-Mobile) as well as carriers in Australia, New Zealand, China, Hong Kong, and India.
So, both the iPhone 8 Plus with model numbers A1864 & A1898 are referred to as the iPhone 8 Plus (Globalà with firmware identifier iPhone10,2.
The other two models are the iPhone 8 Plus (GSM) and have as firmware identifier iPhone10,5.