Why does Google Chrome on Android has so many permissions?
so yes permissions:

pair and acces bluetooth - this is STANDARD for some sites in html/html5 , if browser wouldn't have this permission some website could be broken.
read contacts - it's a next html api and also can break some sites if disabled.
install packages/download files - you think that you can't download things from internet? just look at clouds, github (and other similar sites), pages for converting media types, etc.
find accounts on device - for logging in to your google account which can be use for f.e. : tabs and bookmarks

and if you think that sites doesn't require some permissions look at my game : https://hacknorris-notyetbanned.github.io/glitched.github.io/game/index.html (yes it's self-advertisement but it'd answer your question i think...)
and a few sources with these and a few similar permissions and API's for use by YOU : https://www.w3schools.com/js/js_api_geolocation.asp ; https://developer.mozilla.org/en-US/docs/Web/API/Contact_Picker_API ; https://developer.mozilla.org/en-US/docs/Web/API/Web_Bluetooth_API ;
and if about not showing these permissions in system - it may be due to ROM on your phone.