@SwapnilBhole ,
it's not in focus because camera isn't producing frames to run 3A (auto focus, exposure, whitebalance). You can create Script node and just discard preview frames so 3A is run and frames are in focus.
script_discard.setProcessor(dai.ProcessorType.LEON_MSS)
script_discard.setScript("""
while True:
node.io['preview'].get()
""")
cam.preview.link(script_discard.inputs['preview'])