Hmm ... It's impossible ;-) This RPM doesn't exist on any FTP server

Provides :
pkgconfig(Qt5WebSockets)
qt5-qtwebsockets-devel
qt5-qtwebsockets-devel(x86-64)

Requires :

libc.so.6()(64bit)
libQt5Core.so.5(Qt_5.9)(64bit)
libQt5Core.so.5(Qt_5)(64bit)
libc.so.6(GLIBC_2.2.5)(64bit)
libc.so.6(GLIBC_2.14)(64bit)
libQt5Qml.so.5()(64bit)
libQt5Network.so.5()(64bit)
rtld(GNU_HASH)
libstdc++.so.6()(64bit)
rpmlib(PayloadFilesHavePrefix) <= 4.0-1
qt5-qtwebsockets(x86-64) = 5.9.7-1.el7
libpthread.so.0()(64bit)
libQt5Core.so.5()(64bit)
pkgconfig(Qt5Network)
rpmlib(FileDigests) <= 4.6.0-1
rpmlib(CompressedFileNames) <= 3.0.4-1
pkgconfig(Qt5Core)
libstdc++.so.6(GLIBCXX_3.4)(64bit)
libstdc++.so.6(CXXABI_1.3)(64bit)
libc.so.6(GLIBC_2.4)(64bit)
/usr/bin/pkg-config
libQt5WebSockets.so.5()(64bit)
libm.so.6()(64bit)
qt5-qtbase-devel(x86-64)
rpmlib(PayloadIsXz) <= 5.2-1
libgcc_s.so.1()(64bit)
libQt5Network.so.5(Qt_5)(64bit)
libQt5WebSockets.so.5(Qt_5)(64bit)
libQt5Qml.so.5(Qt_5)(64bit)

Content of RPM :
/usr/include/qt5/QtWebSockets
/usr/include/qt5/QtWebSockets/5.9.7
/usr/include/qt5/QtWebSockets/5.9.7/QtWebSockets
/usr/include/qt5/QtWebSockets/5.9.7/QtWebSockets/private
/usr/include/qt5/QtWebSockets/5.9.7/QtWebSockets/private/qdefaultmaskgenerator_p.h
/usr/include/qt5/QtWebSockets/5.9.7/QtWebSockets/private/qsslserver_p.h
/usr/include/qt5/QtWebSockets/5.9.7/QtWebSockets/private/qwebsocket_p.h
/usr/include/qt5/QtWebSockets/5.9.7/QtWebSockets/private/qwebsocketcorsauthenticator_p.h
/usr/include/qt5/QtWebSockets/5.9.7/QtWebSockets/private/qwebsocketdataprocessor_p.h
/usr/include/qt5/QtWebSockets/5.9.7/QtWebSockets/private/qwebsocketframe_p.h
/usr/include/qt5/QtWebSockets/5.9.7/QtWebSockets/private/qwebsockethandshakerequest_p.h
/usr/include/qt5/QtWebSockets/5.9.7/QtWebSockets/private/qwebsockethandshakeresponse_p.h
/usr/include/qt5/QtWebSockets/5.9.7/QtWebSockets/private/qwebsocketprotocol_p.h
/usr/include/qt5/QtWebSockets/5.9.7/QtWebSockets/private/qwebsocketserver_p.h
/usr/include/qt5/QtWebSockets/QMaskGenerator
/usr/include/qt5/QtWebSockets/QWebSocket
/usr/include/qt5/QtWebSockets/QWebSocketCorsAuthenticator
/usr/include/qt5/QtWebSockets/QWebSocketProtocol
/usr/include/qt5/QtWebSockets/QWebSocketServer
/usr/include/qt5/QtWebSockets/QtWebSockets
/usr/include/qt5/QtWebSockets/QtWebSocketsDepends
/usr/include/qt5/QtWebSockets/QtWebSocketsVersion
/usr/include/qt5/QtWebSockets/qmaskgenerator.h
/usr/include/qt5/QtWebSockets/qtwebsocketsversion.h
/usr/include/qt5/QtWebSockets/qwebsocket.h
/usr/include/qt5/QtWebSockets/qwebsocketcorsauthenticator.h
/usr/include/qt5/QtWebSockets/qwebsocketprotocol.h
/usr/include/qt5/QtWebSockets/qwebsockets_global.h
/usr/include/qt5/QtWebSockets/qwebsocketserver.h
/usr/lib64/cmake/Qt5WebSockets
There is 11 files more in these RPM.