bluetooth/init/prj_ctlr_central_ext.conf

CONFIG_BT=y
CONFIG_BT_BROADCASTER=n
CONFIG_BT_PERIPHERAL=n
CONFIG_BT_OBSERVER=y
CONFIG_BT_CENTRAL=y
CONFIG_BT_EXT_ADV=y
CONFIG_BT_CTLR_ADV_EXT=y
CONFIG_ZTEST=y