Can I know what is this command for, "ip bgp-community new-format" ? If I am not using BGP community string, do I need to enable this command?
This command changes the way the community string value is displayed in various reports. It does not modify the binary format of the community string as sent in BGP messages. It is purely about how you see the community value displayed in, say, various show ip bgp commands.
For detailed information about this command, see the following link:
Using it does not harm even if you are not using communities.