Enumerate NTLMv1

You need at least local admin privilege on the remote target, use option --local-auth if your user is a local account

Enumerate the LmCompatibilityLevel on the remote target via the remote registry:

nxc smb <ip> -u user -p password -M ntlmv1
SMB         <ip>   445    <FQDN>            [*] Windows 10 / Server 2019 Build 17763 x64 (name:<FQDN>) (domain:<FQDN>) (signing:False) (SMBv1:None)
SMB         <ip>   445    <FQDN>            [+] <FQDN>\user:password (Pwn3d!)
NTLMV1      <ip>   445    <FQDN>            NTLMv1 allowed on: <ip> - LmCompatibilityLevel = 2

Outgoing NTLMv1 connections are enabled when the target’s LmCompatibilityLevel is lower than 3.

Network security LAN Manager authentication level - Windows 10MicrosoftLearn