Yes! All of the password managers I recommend for Firefox users are extremely safe — they use AES 256-bit encryption or similar, have zero-knowledge architecture, provide a range of two-factor authentication options, and come with additional features like password auditing, dark web monitoring, cloud storage, emergency access, and more.
Some password managers also include unique features for added security. For instance, Dashlane has a VPN with unlimited data, and Keeper has an encrypted messaging app.