Hey! I have some old website created with muse, my question is if there is a method to insert google recaptcha v3?
I don`t think so - you may insert the code inside an iframe box in Muse but I have no clue if that is working in any case.
You will need full access to the source code. And the only way to do that is by exporting your Muse project to HTML and using a real code editor. Also you can NEVER use Muse again.
Best advice, stop using Muse now. Rebuild the site with better tools that give you full access to your code.
-- Adobe Brackets (open source) - http://brackets.io/
-- Adobe Dreamweaver CC - https://www.adobe.com/products/dreamweaver.html
-- Pinegrow - https://pinegrow.com/
-- Visual Studio Code (open source) - https://code.visualstudio.com/