I'm guessing you don't have this machine yet, so you can't just try it. This isn't a JRiver question, it's a Lenovo question.
The answer is you probably can. DisplayPort supports it. But I can only do so much in trying to help you. The page you linked to doesn't provide the necessary information, and Lenovo has a plethora of different SKUs called the 15 G2 so it's hard for me to find the critical information and be sure it's the right machine, so I'll point you in the right direction and you'll have to do a bit of work yourself.
There are exactly two ways you can play that to your TV: DLNA (if it's a smart TV) or through the DisplayPort output on the laptop.
If you want to do DLNA and the TV supports it, then yes you can.
Otherwise, it's totally dependent on the maximum resolution and refresh rate your specific laptop supports through its DisplayPort output. Many laptops can output higher resolutions than their built in display can handle. That is normal. But the exact capabilities vary from model to model and chipset to chipset. The specs you linked to don't mention it.
So you will need to call Lenovo tech support and ask them. "What is the maximum resolution and refresh rate using DisplayPort on this specific laptop? Does it do 2160p @60Hz?" Then you'll have your answer. Have them point you to the exact detailed spec sheet for that SKU.
Good luck, I hope this helps.