Thank you the Magisk is working now!You should read my posting in Github:
User bleckdeth has made a simple patch at 16.03.2021.
Magisk 21.2 cannot be installed on Sony Z1c with Android 10 Lineage 17.1 · Issue #3636 · topjohnwu/MagiskDescription The last Magisk version that could be correct installed was 20.4. All versions after 20.4 fail (from the first canaries to 21.2 magisk-debug_6d88d8ad). 1.1 Flashing magisk-debug_6d88d8a...github.com
It works perfect but you have to make it after every LOS Update because LOS overwrites the boot image :-(