This would only work when you downloaded the packages to your machine cache as Stefan did (–download-only). That means you have to exchange the path with the actual mirror path:
rpm -Uhv https://download.opensuse.org/tumbleweed/repo/oss/x86_64/libzypp-17.31.28-1.4.x86_64.rpm https://download.opensuse.org/tumbleweed/repo/oss/x86_64/zypper-1.14.68-1.3.x86_64.rpm https://download.opensuse.org/tumbleweed/repo/oss/x86_64/libsolv-tools-0.7.28-1.3.x86_64.rpm