Depends on use, if one is for gaming and the other is for web/YT/etc then you could hook up your monitor for gaming to the GPU and if you CPU has a iGPU then connect the other monitor to the motherboard and enable the iGPU in the BIOS.
Or if your GPU has a DVI port then use a DVI to HDMI adapter. If it's a GTX 10XX series GPU you will need to make sure it's active.