Hi Tpawan Das @Pawan Das ,
the BOOT bit usage is slightly different and refers to the restore of the factory calibration values inside reserved registers (00h - 06h, 0Eh, 10 - 1D), tha could be accidentally overwritten during the device operation.
More specifically (see lis2dw12 datasheet, p.18):
The trim values are stored inside the device in nonvolatile memory. Any time the device is turned on, the trimming parameters are downloaded into the registers to be used during active operation. This allows using the device without further calibration. If an accidental write occurs in the registers where trimming parameters are stored, the BOOT bit in CTRL2 (21h) can help to retrieve the correct trimming parameters from nonvolatile memory without the need to switch on/off the device. This bit is automatically reset at the end of the download operation. Setting this bit has no impact on the control registers.
Best regards,
-Eleon