Using macros with only one input and efficiency questions.

Is it possible to use macros with only one input? for example function example:function with entity @s Pos[1] is a valid command but I don't know how I would reference the value I've passed with a macro because it's just one number.
Is it possible to do this or do I need to pass all the player data to the command and then reference Pos? in this case I don't think I can get Pos[1] specifically in the macro right? So do I need to save it to storage and run the command with that?
I was also wondering if there's much of an effect on performace between running a command with a single value vs running it with all the player data, or does it not really matter how much data you're passsing to a macro function?