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It’s amazing how many little, hard to notice, things affect our hand position on the guitar neck. @Crabby mentioned several things that affect our hand position. Changing the angle of the guitar from horizontal by bringing it up some. Also, not having the guitar square to our body, but having it at an angle with the headstock farther away.
There are a few more things I would mention. For some chords, the elbow is away from the body and for other chords your elbow is tucked into the side of your body. Also, your wrist can be pushed out or rolled back. Your thumb can be at the top of the neck or moved down to the middle of the back of the neck. And, the thumb can be opposite your index finger or moved over to be opposite the middle of your palm, between the middle and ring fingers. All of these adjustments happen regularly as an accomplished guitar player changes chords, but good luck seeing these slight movements and realizing you need to do that. It takes time.
Stretching and warm ups are something everyone should do every day, but especially beginning guitar players. Tony has an impressively large array of warm up exercises, yet you can easily find others or come up with others on your own. Then there are finger independence exercises. The classic exercise is to put your hand palm down on a flat surface with the fingers spread out and try lifting one finger at a time. Do this regularly if you are a beginner and mix it up, doing different orders and even do it rhythmically. When you get good at it, try lift fingers in sets of 2, especially the middle and pinky and the index and ring.
Hope this helps.
MG 😀