Cable to my iMac for my Samsung T3 SSD

I sped up my 2019 iMac that has a HDD by attaching an external SSD as was suggested in this forum. It has a USB-C to USB3 cable so I plugged it into one of the USB ports. I was wondering since it has a USB3.1 connector on the SSD if I can use a USB-C to Thunderbolt cable. The only USB-C cable I have is the one that I used on a previous MacBook Pro power adapter. Is that a fully functional cable ? If not, can I go out and purchase any Thunderbolt 3 cable in whatever length I want? The SSD is rated for 450MB/s and I am getting the following with the USB cable: Write speed: 395 MB/s Read speed: 436 MB/s. So the question is, can that be improved by connecting to Thunderbolt ?