The cr_cronet script is primarily development aid, so it targets default configuration used for testing.
The easiest way to create configurations for different cpus is to modify command line printed by 'cr_cronet.py gn', for example
$ components/cronet/tools/cr_cronet.py gn
Namespace(asan=False, command='gn', gn=False, iphoneos=False, out_dir=None, release=False)
[]
gn gen out/Debug --args='use_errorprone_java_compiler=true arm_use_neon=false target_os="android" enable_websockets=false disable_ftp_support=true use_platform_icu_alternatives=true disable_brotli_filter=true is_component_build=false ignore_elf32_limitations=true'
Done. Made 12946 targets from 1068 files in 3184ms
$ gn gen out/Debug-x86 --args='use_errorprone_java_compiler=true target_os="android" enable_websockets=false disable_file_support=true disable_ftp_support=true use_platform_icu_alternatives=true disable_brotli_filter=true is_component_build=false ignore_elf32_limitations=true target_cpu="x86"'
Done. Made 12955 targets from 1067 files in 3261ms
Build cronet_package target in each build directory:
$ ninja -C out/Debug-x86 cronet_package
And combine content of out/<xyz>/cronet into one folder.
This is pretty much what official builders do.