I think the OP needs to explain the "real" problem. Nothing happens in zero time. Even electrons take a finite time to fly around the nucleus.
Sometimes it's helpful to re-read the initial posts.
Is it possible to set two or more pins to HIGH at the same time ?
The simple answer "yes, if they are on the same port; no, if they are on different ports."
And "yes, if you write a byte to that port; no, if you use Arduino IDE"
.. was given immediately and the OP confirmed that his question was answered ;)
Another thing to keep in mind, children: Digital computing IS SLOW by its nature.
( Nowadays my TV takes longer to start than 50 years ago, when it had to heat up valves. )