I have an iPhone running iOS 12. Is there anyway to change the travel type as I walk a lot so that it automatically gets walking directions where possible and shows travel times as walking times?
This can be changed in Settings -> Maps -> Preferred Transport Type.
Change it to walking or your choice of transport.
When you set your mode of transport it will automatically give directions for that transport type:
The type can still be changed manually if you are using another mode of transport but it will be set to your choice by default.