I'm sure this is what you meant.
To use this, simply go to the location you want the end portal frame to teleport you and then type /setendlocation . Once done that, step on a end portal frame and see if it works.
on step on end portal frame:
teleport player to {endportallocation}
command /setendlocation:
permission: admin.setendlocation
trigger:
set {endportallocation} to player's location
send "&aSet the location to &2%{endportallocation}%"