when going to the end and using a nether portal in creative mode by using fill command will

make minecraft bring you to the overworld and you can move around but minecraft will always think you are in the spot where you came back so you can only interact with stuff near where you spawned

you can replicate this by

making a command block spawn particles where you are using execute command

then go the end

then use the fill comand to make a portal

go in to the portal

and the particles will show you where minecraft thinks you are