I am using simple ion-range. I want to increase the size of the knob of the ion-range. How to set the width and height of the knob?
If you look at the documentation (https://ionicframework.com/docs/api/components/range/Range/) you will find the corresponding sass variables.
$range-ios-hit-width
$range-ios-hit-height
$range-ios-knob-width
$range-ios-knob-height
You will also find the md settings for Android there 
where and how to set these values? i mean in my scss file or my ts file?
The best place would be the variables.scss file in your theme folder
Definitely yes! 