I have a Apple MacBook Pro 13 inch early 2015 model. It has the upgraded 3,1 GHz i7 dual-core in it. Is this possible to output to two 4k monitors on my macbook?
According to Apple's tech specs for the 2015 13" MBP, it is possible: "Simultaneously supports full native resolution on the built-in display and up to 3840 by 2160 pixels on up to two external displays..."
Your model of MacBook Pro came with the integrated Intel Iris Graphics 6100 graphics card that can utilise up to 1.5 GB shared from main memory.
This is capable of supporting an HDMI-compatible device, including 4K, while using one Thunderbolt Display, or supporting up to two Thunderbolt displays.
In terms of actual resolution outputted to an external display, it supports up to 3840x2160 pixels at 30Hz or 4096x2160 pixels at 24Hz (HDMI), or up to 3840x2160 pixels at 60Hz on two external displays via Thunderbolt 2.
So to summarise all that in terms of your scenario of two external monitors, your computer supports a simultaneous maximum resolution up to 3840x2160 pixels on two external displays via Thunderbolt 2.
Alternately, these models can support a single display up to 3840x2160 via Thunderbolt 2 and a single 1080p display (i.e.1920x1200) via HDMI.
You will need to ensure the LG monitors you want have the ports/cables you need to use with your MBP in the way you want (i.e. as two simultaneous 4K screens) otherwise you may require an adaptor or be better served with monitors already providing the ports you need.