Yes, Maya 2019 ships with 1.4.0, which should be able to render 4k on CPU and on GPU.
1.3.0 did not allow for the GPU engine and could only render 2k on CPU, as there was some large stability problems that were resolved with an engine upgrade for 1.4.0.
We're finalizing 1.4.1 currently which fixes a few issues in 1.4.0, which will be the public release for the 1.4.X versions, which will include Maya 2018 as well.