Everytime someone requests something or uses the commands it says "Server:" Is there a way to change that to a different name to fit the server style?

Which requests and commands are you referring to?

anything that the server messages. 
for example: 

Those are generally set by the plugin being used to send the message, else it defaults to SERVER in Oxide and Rust. So that change would either be per plugin you are using or via command replacement for things such as "say".

im assuming theres no way to force it?

Generally not, as that's something each plugin can control on their own.

Plugin BetterSay will do what you ask.

Correct you will need to edit all your other plugins aswell. but that will handel the ones using say.