feature does a good job of stating which of its features are experimental.

The 'class' feature

WARNING: This feature is still experimental and the implementation may change or be removed in future versions of Perl. For this reason, Perl will warn when you use the feature, unless you have explicitly disabled the warning: [...]

---

warnings lists all warning classes.

     |
     +- experimental --+
     |                 |
     |                 +- experimental::args_array_with_signatures
     |                 |
     |                 +- experimental::builtin
     |                 |
     |                 +- experimental::class
     |                 |
     |                 +- experimental::declared_refs
     |                 |
     |                 +- experimental::defer
     |                 |
     |                 +- experimental::extra_paired_delimiters
     |                 |
     |                 +- experimental::keyword_all
     |                 |
     |                 +- experimental::keyword_any
     |                 |
     |                 +- experimental::private_use
     |                 |
     |                 +- experimental::re_strict
     |                 |
     |                 +- experimental::refaliasing
     |                 |
     |                 +- experimental::regex_sets
     |                 |
     |                 +- experimental::try
     |                 |
     |                 +- experimental::uniprop_wildcards
     |                 |
     |                 +- experimental::vlb
     |
[download]

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And yes, experimental also lists all experimental features.

class - enables the class, field, and method syntax

This was added in perl 5.38.0.

The addition of class, keyword_all and keyword_any was simply overlooked for a while. You need to upgrade the module (0.036) to its latest version to get these.

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Finally, I've been updating Perl named operators and builtin subs introduced since 5.6, which includes precise information as to when the items were experimental. However, this focuses on named operators and builtin subs (including, for example, class) rather than features.