Hi, All the assets along with the pages of an AEM site are present in /apps/content hierarchy in the CRXDE. If you have permissions, you should be able to access the prod's CRXDE using this URL: https://[host]:[port]/crx/de
You can make a package for the same or only the things you want from it by using prod's package manager: https://[host]:[port]/crx/packmgr
To create a package, click on Create Package and give a name to your package.
Now you will see an empty package is created. Now click on edit > filters > add filter
In the root path add the path for the asset that you also want in dev and click on done. Similarly, you can add multiple asset paths by clicking the add filter button again and again.
After adding all the paths, you can click on save.
Now, you have to click on the build button and after successful build you can click on download. This will download the required prod package.
You can now install this package in your dev's CRXDE. To do so, you can click on upload package in the package manager (make sure you open dev's package manager only). Select the prod's downloaded package and check the force upload. Now the package has been uploaded, all there is to install the package by clicking on install.
After installing the package you will see, your dev and prod assests are in sync now.
Note: I suggest you to not make the whole package of /content as it can be very large in size. Select individual asset paths that you really need and make a package for the same.
Fact: For the same task, reverse replication agents are also setup. You can also take help of them.