I know how the Metasploit framework works and I know that it can generate payloads and such, my question is if there is a way to evade anti-virus using Metasploit payloads. What exact purpose does it serve, can I create something on my own and add it and increase my attack vector using the Metasploit framework?
Metasploit Framework is a complex tool that can create payloads, receive connections from backdoors, launch exploits, run auxiliary scans (vuln scans, port scans, discovery scans, etc...). If you're looking at evading AV, you may have some success with MSFVenom.
I'd suggest starting off by reading the Metasploit documentation @ https://metasploit.help.rapid7.com/docs/getting-started