Here are the simple things you need to be aware of and understand before you begin to learn the guitar. Pay attention to these things, and you will be successful on guitar.

Body Awareness
The awareness of the physical body and especially all the muscles needed to play the guitar, must be much greater for the guitar player than it is for the average person. In normal life, we never need the same kind of fine motor control that we need in playing the guitar. Everyone has a different amount of natural awareness of their body, some have a lot, some have a little. The important things is: everyone can increase the awareness they do have, by using certain techniques.
All the muscles in your body are connected. The movement of one muscle affects the condition of other muscles. The movement of one finger tenses the finger next to it. In the beginning, every time you move a finger, you will be tensing up other fingers. Every time you move your arm, you will be unknowingly tensing other parts of your body.
This is called Sympathetic Tension. It is your greatest enemy in learning guitar. Excess tension in the muscles, especially the muscles of the arms and hands, is deadly to playing the guitar. It will either severely limit your playing ability, or it will prevent you from developing any playing ability. Why?

Muscle Memory
Your muscles remember everything they do, even the tension they feel. Because of this fact, the tension you unknowingly create during practice will be locked in to the muscles. Right from the beginning, this tension will make all finger movements feel difficult, or impossible. You will begin to develop habits of tension as part of how you play the guitar. You will think these uncomfortable feelings are normal, the way it is supposed to be.
As time goes by, you will start to become unaware of feelings of tension, as you pay less and less attention to them. The longer this goes on, the worse shape you will be in, and the more work will be required to become aware of, and undo these knots of tension.

Body Tension Destroys Finger Control
These knots of tension will make you lose control of your fingers while playing, especially playing fast, and especially in front of other people. When you have trouble playing well, and when you see other people do things you can’t do, you will think they have more talent than you do.
You won’t know that if you did not have the physical tensions locked in to the muscles needed to play, you would be able to do what they are doing.

Don't Hold Your Breath!
When you are trying to do something difficult on guitar you will hold your breath. Every guitar student I have ever seen does this, including me if I am not careful.
I guarantee that you frequently hold your breath while practicing and playing. If you are smart, you will start playing attention to yourself in this way, because when you hold your breath, you prevent energy from going to your fingers.
Pay attention to your breathing the next time you practice. Especially on the parts you struggle with - you will discover that you are holding your breath!
Asking about the above muscle memory and tension that you're talking about. What to do to avoid it? Please tell me. I m feeling fatigue in my hand too. Sometimes unable to change between chords.
You have to have whole body awareness as you practice. Read this….https://www.guitarprinciples.com/whole-body-awareness-for-maximum-guitar-improvement/