hi anyone please suggest where can we find the model file of sky130_fd_pr__nfet_03v3_nvt...so that we can use this for designing purpose

$PDK_ROOT/sky130A/libs.ref/sky130_fd_pr/spice/sky130_fd_pr__nfet_03v3_nvt.pm3.spice

. But normally you don't need to know where the model is. If you just want to understand the devices, look at https://skywater-pdk.readthedocs.io/en/main/rules/device-details.html#id13. Make sure you are using this device for the right reason. You want a native Vt device (essentially zero threshold)?