So this time bitcoin core is trying to fork?
I you're talking about Segwit 2X then no.
Core has wanted Segwit for years. Now it's going to happen, but instead of people accepting Segwit (which they refused for years) they accepted Segwit2X = Segwit + 2MB blocks. The Segwit part is a tested piece of code (could still have bugs though), the 2X is untested, not made by Core.
- core nodes will not recognise segwit2x blocks, so these will not be added to the core chain. At the same time 2x has no replay protection, so transactions that occur on the 2x chain can be mirrored on the core chain. It's going to be a shitshow , in my personal opinion.