Multiboxing, or playing multiple World of Warcraft accounts at once, is not a violation of our End User License Agreement. Please note, however, that use of all software or hardware mechanisms used to mirror commands to multiple World of Warcraft accounts at the same time, or to automate or streamline multiboxing in any way may result in account penalties.
https://eu.battle.net/support/en/article/24258#:~:text=Multiboxing%2C%20or%20playing%20multiple%20World,our%20End%20User%20License%20Agreement.