Before you go spending a load of money on a stock, there is plenty to do and research.
First off, better kit is to help you improve when you have mastered everything else, like position, trigger grip and technique etc.
The following are generalisms. So,
Spend more time shooting or practicing. Spend more time practicing with an air rifle. Most people do not shoot enough, (me also) yet expect to be getting bullet on bullet at 100 yards when shooting from the hip. That is usually the biggest thing to master.
Master the technique, your breathing, your trigger, first.
Shooting off a bench or the ground, using bags where you are well balanced and rested is going to give you a tighter group than shooting off quads stick or twin sticks, as an example.
Your head position is going to be different, from a lying position to a standing position, this can also affect accuracy.
Your head should set up to the position that you shoot from the majority of the time.
Type of bullet used can affect accuracy.
Once your technique is sorted you can then look at fit in detail.
look at some videos of shotgun fit. There are loads of them, they explain how to understand cheekweld etc. experiment with bits of foam taped to your rifle for fit. There are one or two rifle fit videos out there, mainly American, they can be difficult to find. There may be more now as it has been a few years since I looked. But, they are definitely worth watching.
Most stocks are designed for an average sized person, normally 14 and 1/4’ lop I think. If you are an average size person, then you may not need to change anything. I, on the other hand, am a bit weird, and standard rifles do not fit me, at all, hence why I went down this journey. If ever any one advises you to, put the stock of your rifle in the crook of you arm and the measures that for lop, walk away, there is so much more to it, are you a fat git, or a beanpole, wide shoulders, narrow? Everything affects fit. Also, the clothes you wear, in the winter we tend to wear more so thicker.
In conclusion, Sort out the basics first, then experiment with foam on rifle, then, once you know your measurements for where you need to be, then and only then you can consider getting a new stock.
I once went to an archery day, shooting recurve and longbows, and we asked the guy running it about the Olympic bows with weights and fancy things. His answer was, “when you can consistently put an arrow in a two pence piece grouping, then you can consider going for one of those.”