One of the problems that you will face when buying a replacement windscreen is the fact that your bike is so new.
I guess I should inquire first as to what your country is. This may make getting some brands harder to find than others.
Next, you should look online at the various styles and heights each manufacturer offers. There are 2 heights offered, mid-height and tall.
Givi is a favorite, but is not the only manufacturer of windscreens for the PCX.
National Cycle is another manufacturer. There are also others that may not be a popular.
The main difference between Givi and National has to do with the width of the screens. I personally like Give because my hands have some coverage, though you can as well purchase some hand windguards for your scooter.
From my viewpoint the tall ones work best because almost all of the wind is blocked/diverted with those, while on the mid height ones the wind will hit you in the chest.
Once again, preference. Also, location. Perhaps if you lived in the tropics you would WANT the wind to hit you in the chest in order to stay cooler.
On the other end of the scale, if you get a tall screen you may feel a "sail" effect in higher winds. This can be compensated for by changing your riding habits slightly. Others on this forum have discussed this considerably so you should be able to find something .
Here is but one of the discussions:
https://www.hondapcx.org/viewtopic.php?f=7&t=5538
Your first job would be to determine if Givi or National has a windscreen for the 2019 PCX. Then you can do additional research.
only problem is I find the screen is much too small and does nothing!
Congrats on choosing the PCX and enjoying the ride. 
