Not necessary. Beneficial. Advantageous. Also: not beforehand. You don’t need to know the truth in every aspect in advance of experience. Experience is the best way to get it! You proceed with the best grasp of truth available, current best, best so far. You hold it forward in the world with both hands and you see what comes to knock it out!
Any better grasp that comes is now yours. Trade up. As you move through the world upgrading your grasps every time each falls short, casting aside the misfit or false grasp for better and best, your truth will improve and improve everywhere you contact reality. You’ll quit fearing finding yourself wrong, too, because you’ll have learned: finding wrong always opens the way to find right.
Truth is correspondence with reality. That is all truth is. We want to improve our grasp of truth because it means more points in contact with reality when we exert force, and a more realistic aim in how we angle it to desired goals. We ease and brighten our consequence of being. We get better outcomes, and more of our chosen outcomes, the more we improve our grasp on whatever it is we have in front of us and all around. Whatever we bring ourselves to bear upon.
The main thing truth sets you free from is doing it the stupid, ineffective way next time. And every step along that path adds sureness, strength and if you wish, speed to every next step, and every step thereafter.
So mostly I’d say it is necessary (well, beneficial) to seek the truth in every aspect in order to live better. But you seek it actively, in being. In doing. You seek it in the test. You take the best grasp you have as your premise and you act from it, as if. Every act from a premise is a test of its premise. In thoughtful aim, thoroughly-known and weighed values and priorities, well-chosen goals, and ownership of all consequence from every course you choose, you find better and better premises, and you never stop looking to better them. It is in self-ownership and examination of consequence that every lesson we have to learn is best and most readily grasped.
Truth is an objective point of view. As human beings we are subject to various self-driven forces that tend to dull the effects of raw Objective Truth in favor of a more subjective one that sets ourselves in a good light regardless of the reality. Can we ever arrive at the unvarnished Truth on our own efforts? I would despair if I thought that we had to for some meta-physical reason. It certainly doesn’t happen for more earthy reasons.
The quote from the Bible (the Gospel of John 8:31–32) is an important step on the way towards Truth, should we decide to pursue it.
31 So Jesus said to the Jews who had believed him, “If you abide in my word, you are truly my disciples, 32 and you will know the truth, and the truth will set you free.”
To gain Objective Truth, even in the limited way we can in this self-centered world in which we live, requires a point of reference outside the experience of being human. I have investigated some meta-physical sources of Truth and found that the Christian Worldview (properly pursued) is the closest to a way that aligns with my lived experience and what I have uncovered about the Real Reality surrounding us. Jesus Christ didn’t come with a message. He was and still is the message. It would do a person well to investigate his claims of bringing redemption to us all.