There is no 11.6 update.
If you mean 11.2.6, the answer is no. It's not meant to.
iOS 11.2.6 includes bug fixes for your iPhone or iPad. This update:
- Fixes an issue where using certain character sequences could cause apps to crash
- Fixes an issue where some third-party apps could fail to connect to external accessories
For information on the security content of Apple software updates, please visit this website: https://support.apple.com/kb/HT201222
So check out the suggestions for speeding up your iPhone here.