It is clear that although you apparently know what you want to get as a finished product, you are very unclear as to how to go about it, as Russell notes.
Even though this is an incredibly broad question, I will give you a rough guide which hopefully will show you that this task is not a simple matter of looking at a bunch of break-out boards and amalgamating the functions from simply looking at them.
The design of a PCB starts with a set of requirements (at system level is best). It is critical that this is done properly; after all, if the requirements of your PCB are not clear, nobody can realise a reasonable result. Note that this can take a long time to be done properly.
The requirements include specifically what function(s) the PCB must provide, and can also have a requirement that the PCB is powered by some particular voltage(s). This is a very simplistic overview of quite a complex process.
At that point, if you intend to copy the result you have from breakout boards, you can try and define the IC(s) used for each breakout board function; you may run into significant difficulty here as many Chinese breakout boards have cheap knock-off devices with indecipherable part numbers - in that case, you need someone experienced in the design of those function(s).
This leads to a system or architectural diagram that clearly shows what is going on at a reasonably high level, but can guide a designer to choosing the correct devices to achieve that result.
The next step (assuming you have chosen appropriate and available devices) is schematic capture; this can take quite a bit of time, depending on the complexity of the design.
If your PCB is very complex, then pre-layout simulation may well be prudent. Depending on the complexities involved, you have a range of tools available ranging in cost from free to many thousands of dollars (or pounds for that matter).
Once you have a PCB form factor defined, you can move to PCB layout; once more, depending on the complexities involved, this can be a time consuming activity. The layout of a PCB is part of the hidden schematic (there are electrical effects that may not be apparent from the actual schematic design).
Post-layout simulation may be appropriate (which can lead to changing the layout). There are numerous simulation tools and some support both pre- and post-layout functionality.
Note that PCB layout designers are not necessarily electrical designers; Although a lot of electronics designers can drive layout tools, the opposite is not as true.
At the end of this stage, you will have a set of gerber files or perhaps an ODB++ database. This is what you can send to a PCB fabricator.
Once you have these in your hand, you could engage a PCB assembly contract manufacturer to actually put the parts on the board for you and perhaps do a functional test (that needs to be defined by you or whoever you get to actually do the tasks above).
I have left large holes in this (such as independent reviews - we can all make mistakes), but hopefully you get the idea this is not a simple set of tasks.