5.1.1.2: "Verifiers SHALL require subscriber-chosen memorized secrets to be at least 8 characters in length. Verifiers SHOULD permit subscriber-chosen memorized secrets at least 64 characters in length." [1]
I use a common password manager and its max generated password length is 64, so it's in agreement with NIST. That said I am able to manually add characters to increase beyond 64.
Yeah, you should be storing the password hashes in the DB, not the passwords. The hashes are going to be the same length regardless of the password's length.
If you wanted to get real fancy, hash the password once on the client side (reducing it to a known length), then again on the server. You should also be using a per-user salt to prevent a rainbow table from being generated if your DB is leaked.
5.1.1.2: "Verifiers SHALL require subscriber-chosen memorized secrets to be at least 8 characters in length. Verifiers SHOULD permit subscriber-chosen memorized secrets at least 64 characters in length." [1]
[1] https://pages.nist.gov/800-63-3/sp800-63b.html or https://doi.org/10.6028/NIST.SP.800-63b