But Bitwarden has a minimum of 2 words, and you wanted it “lower”?! See here:
See this discussion here about “strength testing”: Do you use password strength indicators? Complete this survey!
And this discussion about entropy (estimations): Discussion of Passphrase Entropy and Entropy Estimation Tools
TLDR: Those strength testing tools are highly unreliable. - And for passphrases the entropy is “nearly stable” per word - adding some numbers etc doesn’t change that much. (given and dependend on the pool of words the phrase is randomly chosen from)