Is It Permissible to Open the Third Eye

According to what has been clarified on the subject, the matter of opening the eye is a complex action made up of physical techniques and concentrated thoughts, reaching the stage of self-nullification.
It is understood that the physical techniques that work to open a person's power of concentration, such as sound frequencies capable of doing so (in a physical and scientific sense), are permitted for use - as is any use of a physical technique that a person employs in order to concentrate better or to perceive, through the path of his imagination, signs to discover what is happening in his inner feelings.
However, the part of the concentration regarding opening the eye that uses expressions and imagery of a real power and energy holder - such as what instructors direct one to imagine a circle and add power to it, or call it by the name of cosmic or universal energy, or ask it where a person's location is within the general energy - all of these are instructions for thoughts forbidden by Judaism, and they border on the severity of the transgression of idol worship. This is especially so when the inner self-nullification becomes, in the imagination of the one imagining it, a false belief and a form of worship, Heaven forbid.
And since it is very difficult to draw the line separating them, and since many of the instructions given in this technique are clearly derived from Far Eastern religions, the process may not be permitted in general. Only if every detail is examined together with the purpose behind it and the benefit it provides, will it be possible for a rabbi expert in these matters to rule which parts are permitted for use and which are forbidden.
And in conclusion I will note that everything found there exists in Judaism with far greater quality and precision. I recommend watching the lecture Far Eastern Wisdom versus Judaism on the Hidabroot website.
And I remain with blessing