I first move the file that I did wrong outside, and than follow your command, with my own OSS version:
ypnano7@ypnano7-desktop:~$ sudo mv /usr/lib/aarch64-linux-gnu/libnvinfer_plugin.so.7.1.3 ~/libnvinfer_plugin.so.7.1.3.bak
ypnano7@ypnano7-desktop:~$ sudo cp /opt/nvidia/deepstream/deepstream-5.1/sources/TensorRT/build/out/libnvinfer_plugin.so.7.1.3 /usr/lib/aarch64-linux-gnu/libnvinfer_plugin.so.7.1.3
ypnano7@ypnano7-desktop:~$ sudo ldconfig
ypnano7@ypnano7-desktop:~$ ll -sh /usr/lib/aarch64-linux-gnu/libnvinfer_plugin.so*
0 lrwxrwxrwx 1 root root 26 6月 6 2020 /usr/lib/aarch64-linux-gnu/libnvinfer_plugin.so -> libnvinfer_plugin.so.7.1.3*
0 lrwxrwxrwx 1 root root 26 2月 10 15:04 /usr/lib/aarch64-linux-gnu/libnvinfer_plugin.so.7 -> libnvinfer_plugin.so.7.1.3*
14M -rwxr-xr-x 1 root root 14M 2月 10 15:03 /usr/lib/aarch64-linux-gnu/libnvinfer_plugin.so.7.1.3*