This processor is not present in NXP SDK file builder.
Hi Raja:
Unfortunately MK20DX256VLH7 is not supported in MCUXpresso SDK.
You can download the bare metal code examples from below link
TWR-K20D72M|Tower System Board|Kinetis MCUs|NXP
Or you can use Classic MQX 4.2 , TWR-K20D72M is supported.
Regards
Daniel