Crunch is the industry standard for wordlist generation. If you are on Kali Linux, it’s pre-installed.
A text file containing every 8-digit combination (one per line) takes up roughly 900 MB of space. 8 Digit Password Wordlist
If you prefer not to generate your own, several reputable sources host large collections of common passwords and numeric patterns: Approach Crunch is the industry standard for wordlist
crunch 8 8 abcdefghijklmnopqrstuvwxyz -o 8-lower.txt 8 Digit Password Wordlist