A useful tool within Google Docs is the speech to text functionality.  You do not need to add an extension or anything. 

It is available from the main menu when you are in a Google Docs document. 

Here are instructions from Google Support...

Type with your voice

1. Check that your microphone works.

2. Open a document in Google Docs with a Chrome browser.

3. Click Tools…. Voice typing....

4. When you're ready to speak, click the microphone.

5. Speak clearly, at a normal volume and pace (see below for more information on using punctuation).

6. When you're done, click the microphone again.

Note: The first time using Voice Typing, you may be prompted to grant permissions to use your microphone.

Tip #1:  From the address bar in your browser, type docs.new to start a new document instantly.

Tip #2:  Another way to activate Voice typing is to press Ctrl+Shift+S in Windows (or Command+Shift+S on a Mac)

Tip #3:  When you’ve finished, instead of clicking the microphone again, you can say “Stop listening".

Tip #4:  Add punctuation by using the following phrases…

• Period

• Comma

• Exclamation mark

• Question mark

• New line

• New Paragraph

Note: Punctuation only works in German, English, Spanish, French, Italian, and Russian.

Tip #5:  You can change the language by clicking the three dots and then use the Language drop-down

to select from over 100 languages and dialects....

Afrikaans, Albanian, Amharic, Arabic, Armenian, Azerbaijani, Basque, Belarusian, Bengali, Bosnian, Bulgarian, Catalan, Cebuano, Chichewa, Chinese, Corsican, Croatian, Czech, Danish, Dutch, English, Esperanto, Estonian, Filipino, Finnish, French, Frisian, Galician, Georgian, German, Greek, Gujarati, Haitian Creole, Hausa, Hawaiian, Hebrew, Hindi, Hmong, Hungarian, Icelandic, Igbo, Indonesian, Irish, Italian, Japanese, Javanese, Kannada, Kazakh, Khmer, Kinyarwanda, Korean, Kurdish (Kurmanji), Kyrgyz, Lao, Latin, Latvian, Lithuanian, Luxembourgish, Macedonian, Malagasy, Malay, Malayalam, Maltese, Maori, Marathi, Mongolian, Myanmar (Burmese), Nepali, Norwegian, Odia (Oriya), Pashto, Persian, Polish, Portuguese, Punjabi, Romanian, Russian, Samoan, Scots Gaelic, Serbian, Sesotho, Shona, Sindhi, Sinhala, Slovak, Slovenian, Somali, Spanish, Sundanese, Swahili, Swedish, Tajik, Tamil, Tatar, Telugu, Thai, Turkish, Turkmen, Ukrainian, Urdu, Uyghur, Uzbek, Vietnamese, Welsh, Xhosa, Yiddish, Yoruba, Zulu