I am afraid it is not expected.
Can you double check below step mentioned above?
Please see below.
Original:
$ ll -sh /usr/lib/aarch64-linux-gnu/libnvinfer_plugin.so*
0 lrwxrwxrwx 1 root root 26 Apr 26 16:41 /usr/lib/aarch64-linux-gnu/libnvinfer_plugin.so → libnvinfer_plugin.so.7.1.0
0 lrwxrwxrwx 1 root root 26 Apr 26 16:41 /usr/lib/aarch64-linux-gnu/libnvinfer_plugin.so.7 → libnvinfer_plugin.so.7.1.0
4.5M -rw-r–r-- 1 root root 4.5M Apr 26 16:38 /usr/lib/aarch64-linux-gnu/libnvinfer_plugin.so.7.1.0
If
$ sudo mv /usr/lib/aarch64-linux-gnu/libnvinfer_plugin.so.7.1.0 ~/libnvinfer_plugin.so.7.1.0.bak
$ sudo cp {TRT_SOURCE}/build/out/libnvinfer_plugin.so.7.0.0.1 /usr/lib/aarch64-linux-gnu/libnvinfer_plugin.so.7.1.0
$ sudo ldconfig
then
nvidia@nvidia:~$ ll /usr/lib/aarch64-linux-gnu/libnvinfer_plugin.so*
lrwxrwxrwx 1 root root 26 Apr 27 08:53 /usr/lib/aarch64-linux-gnu/libnvinfer_plugin.so → libnvinfer_plugin.so.7.1.0*
lrwxrwxrwx 1 root root 26 Apr 27 08:53 /usr/lib/aarch64-linux-gnu/libnvinfer_plugin.so.7 → libnvinfer_plugin.so.7.1.0*
lrwxrwxrwx 1 root root 26 Apr 27 08:55 /usr/lib/aarch64-linux-gnu/libnvinfer_plugin.so.7.0.0 → libnvinfer_plugin.so.7.1.0*
-rwxr-xr-x 1 root root 4652648 Apr 27 08:55 /usr/lib/aarch64-linux-gnu/libnvinfer_plugin.so.7.1.0*