The title says it all, can you Instance.new a script with all the scripting stuff inside it?
You can Instance.new a script using Instance.new("Script") or Instance.new("LocalScript") however ROBLOX no longer lets us edit a script's .Source property from another normal script (I say normal as things like the CommandBar and plugins can still change script.Source)
You could always do the not so secure somewhat alternative and make a script that runs the the value of a StringValue using loadstring()
local strValue = script.Code loadstring(strValue.Value)()
Do note that loadstring() is no longer usable from LocalScripts and in order for it to work in normal server scripts ServerScriptService.LoadStringEnabled MUST be set to true.