Greetings,
Sorry, but this won't work. Here's why. Depending on the CPU, you only get a limited number of PCIe lanes for peripherals or device connections. This is why you are not able to connect a drive to every single SATA port and each m.2 connector. This is not supported.
In order for the you to be able to connect multiple SATA disks to a U.2 connector, you would need to be able to configure it in BIOS to support SATA mode, instead of interfacing the PCIe controller directly on the CPU. The board does not have this support. This is also why you cannot create a mixed RAID array using a combination of M.2 and SATA disks. Its one or the other, not both.
Hope this helps. The X270 is older now by today's standards. Depending on the intended use, buying a newer board and processor could be a better long term investment. I'd double check BIOS and CPU support if you plan to run W11.