There are two ways to do that, one is UI but partially controllability, one is command line args.

UI Approach

1. open chrome://flags page
2. find your feature
3. do your choice
4. restart browser

basically, your choice will save to the user data file, after restart browser, the data will transform to command line arguments.

Command Line Approach

official wiki

Features List

official indexes

Examples

Enable Import Assertions

Currently(v90), there are 3 flags need to be enabled.

you can figure out from real c++ code

1. --harmony-import-assertions

   this flag come from v8 project, you can use command line approach set arg --js-flags="--harmony-import-assertions" to enable it.

2. RuntimeEnabledFeatures::CSSModulesEnabled()

   this flag define under RuntimeEnabledFeatures namespace, you can use ui approach enable Enable experimental web platform features flag.

3. blink::features::kJSONModules

   this flag define under blink namespace, you can use command line approach set arg --enable-blink-features=kJSONModules to enable it.