Hi Pauline,
Yes, the Surface Laptop 3 supports DisplayPort 1.4 Alt Mode via its USB-C port, so you can definitely use a USB-C to HDMI adapter to connect it to your TV for streaming. Just a heads-up: if your laptop has an Intel processor, it supports external display resolutions up to 5120×2880 at 60 Hz. If it's an AMD model, it can go even higher, up to 7680×4320 at 30 Hz or 5120×2880 at 60 Hz. Either way, you're set for smooth, high-quality video on the big screen. For the adapter, Microsoft’s official USB-C to HDMI adapter is a solid choice.
Best,
Jeric