A Thunderbolt cable/dock is capable of transferring 40gbps of data. This is more data than almost anyone could possibly use BUT if you're using your dock to connect to multiple 4k monitors, you may be using more data than you think. Each 4k 60hz monitor is using a steady 15gpbs. If you've got 2, you're using up 30gbps and you've only got 10 left to be split among all of your other peripherals.
So you could buy 2 docks and plug them into different Thunderbolt ports or you could buy the iVanky VCD10 dock that is basically 2 docks in one enclosure. Instead of plugging it in with a single 40gbps Thunderbolt cable, you plug it in with 2 to get 80gbps of bandwidth.
This dock claims to be able to connect to 4, 6k monitors, all running at 60hz, while still having enough bandwidth to power all of the extra ports. What ports you may ask? The most ports I've ever seen on a dock.
The only ports missing from this dock are DisplayPorts but most of these dock makers are recommending you buy USB C to DisplayPort cables anyway.
I personally do not own a Macbook capable of pushing more than 2 monitors but I was able to connect both of my 4k monitors at 60hz as well as every other port (minus the optical audio port) at the exact same time, and the dock did work.
I remember just a few years ago when USB C docks and dongles were the most unreliable products I ever had the displeasure of using. I'm thrilled that they've finally figured it out, and using these docks with a laptop has become one of the most convenient devices I own.
The iVanky 20-in-1 dock is the most expensive dock I've ever seen, but it's also the most feature-rich. It's certainly overkill for the average person, but if you're looking for the most advanced Thunderbolt Dock on the market, this is it.