$ irb
irb(main):001:0> require 'openssl'
=> true
irb(main):002:0> puts OpenSSL::OPENSSL_VERSION
OpenSSL 1.1.1g 21 Apr 2020
=> nil
irb(main):003:0>

又は
$ ruby -ropenssl -e "p OpenSSL::OPENSSL_VERSION"
"OpenSSL 1.1.1g 21 Apr 2020"

Mac ruby 2.0.0におけるDEFAULT_CERT_FILEのディレクトリ情報 #Ruby - Qiita
https://qiita.com/shiro_usagi/items/311be28fa29da54d7f11

irb(main):002:0> require 'openssl'
=> true
irb(main):003:0> p OpenSSL::X509::DEFAULT_CERT_FILE
"/usr/local/stow/openssl-111g/ssl/cert.pem"
=> "/usr/local/stow/openssl-111g/ssl/cert.pem"
irb(main):004:0>

又は

$ ruby -ropenssl -e "p OpenSSL::X509::DEFAULT_CERT_FILE"
"/usr/local/stow/openssl-111g/ssl/cert.pem"

参考
RubyのOpenSSL::OPENSSL_VERSIONはなぜ定数？ / マスタカの ChangeLog メモ
https://masutaka.net/chalow/2014-04-08-1.html