No, you don't need to convert the configuration voltage when an Intel® Arria® 10 device is the master and older technology (pre-Intel Arria 10) Intel® FPGA devices are the slave in multiple devices AS configuration chain.
When an Intel Arria 10 device is used as the master in multiple devices AS configuration, the configuration voltage must be 1.8V. Although older technology Intel FPGA devices do not support 1.8-V configuration voltage in AS configuration mode, the slave devices must be in Passive Serial (PS) configuration mode, and PS configuration supports 1.8-V configuration voltage.
So you can connect 1.8-V configuration voltage to the slave devices directly.
See the above description.