You shouldn’t worry so much about the initial thickness- I think the section size will be more important for you.
For type 1 hair vs type 4 hair, the hairs on the opposite ends of the spectrum, the thickness of locks is relative. For instance, when I say that pencil thick is very thin on straight hair, this is an average thickness for kinky hair.
I just wanted to clarify that I will be talking in relative terms to straight hair in this post.
So, if you’d like very thin locks, make the sections a bit smaller than 1×1 inches.
For thin/medium locks, make sections about 1×1 inches.
For thick locks, make sections about 1.5×1.5 inches.
Your hair thickness and type will have an influence on the thickness of your locks- a 1×1 inch section on someone with thin hair will give thinner locks than a 1×1 inch section on someone with thick hair.
These are just guidelines and rules of thumb.
Again, here I am talking mostly about straighter hair textures:
As your locks mature, you can somewhat influence how much they thicken up. If you want them to thicken up a lot, don’t do any maintenance (aside from washing regularly and separating daily). This will give thicker, wilder looking locks.
If you’d like to steer them to look more tidy and uniform, and to not thicken up as much, do a monthly all-over crochet hooking session. You can flatten out the loops and make sure the locks are keeping a cylincrical shape.
Some videos on crochet hooking can be found here:
root to tip crochet hooking:
fixing flat spots and loops:
Remember that maintenance done in moderation will not harm your locks or hair. Remember also that maintenance is 100% optional and it is up to each person to decide what is right for their hair.
I hope this answer is helpful to you.