When you want to recursively copy files from one directory to another, use find and pipe its output to cpio.
find . -name '*.jpg' | cpio -pdm /path/to/<dest_dir>
This will find all files with extension ‘jpg’ and copy them to <dest_dir> directory. cpio -pdm copies files to destination directory and also creates the directory structure.
find . -name '*.jpg' | cpio -pdumv /path/to/<dest_dir>
This will copy all ‘jpg’ files and replace any existing files unconditionally (-u). -v is the verbose flag.