I have three monitors that I want to connect to my NUC8i7BEH. One monitor is HDMI and the other two are DisplayPort connections. I tried a couple of Thunderbolt 3 adapters already and it didn't work. Can you please recommend which multiple monitor adapter out there that would work with my NUC and preferably one at 60hz.
The USB-C connector is exposing one of the DP channels from the processor. You can use a MST Hub to split this output and support two independent monitors.
Here is a link to such a device on Amazon: https://www.amazon.com/Monoprice-USB-Dual-DisplayPort-Hub/dp/B07D7KLKY1.
Now, you will be splitting the throughput capability of this single DP channel in half. What this means is that you will be able to run two 2K monitors at 60Hz, but you will only be able to run two 4K monitors at 30Hz. The HDMI connector on the same NUC is still capable of supporting a third 4K monitor at 60Hz, however.
Hope this helps,
If you do want to connect multiple 4K / 60 Hz displays it is possible with a USB 3.0 to Displayport adapter.
I have an HP Elite/ZBook Thunderbolt 3 Dock that has two DP output ports, and have successfully used it with my NUC8i7BEH via a 0.5m StarTech Thunderbolt 3 cable, though since I only have one 4K 60Hz display, I could not verify whether this dock can drive dual 4K 60Hz displays.