samples of hostapd and wpa_supplicant are in this directory: applications/sample/camera/communication, you can edit the BUILD.gn and hostapd/config/hostapd.conf or wpa_supplicant/config/wpa_supplicant.conf in this directory.

example of BUILD.gn:

lite_component("sample") {
    features = [
        "wpa_supplicant:wpa_sample", #station
        "hostapd:hostapd_sample" #ap
        #"wpa_cli:wpa_cli_sample" #wpa client
    ]
}

example of hostapd/config/hostapd.conf:

interface=wlan0
driver=hdf wifi
ctrl_interface=udp
# name of this ap
ssid=testap
hw_mode=g
channel=1
ignore_broadcast_ssid=0
# following use wpa2-psk encrypt type
# you can omit this if going to setup an open ap
auth_algs=1
wpa=2
wpa_passphrase=12345678
rsn_pairwise=CCMP

example of wpa_supplicant/config/wpa_supplicant.conf:

country=GB
ctrl_interface=udp
network={
    #which SSID to connect to
    ssid="example"
    # key_mgmt=NONE if connect to an open ssid
    #key_mgmt=NONE
    # or use psk to suply the password of that ssid
    psk="12345678" 
}

Suppose the wireless interface is wlan0, after build and burn the new image to your device, you can then execute the following command to connect to an existing network:
exec /bin/wpa_supplicant -i wlan0 -c /etc/wpa_supplicant.conf
or execute this command to connect to an existing network:
exec /bin/hostapd -i wlan0 /etc/hostapd.conf

hope this would be helpful.

@Caoruihong thank you very much. I will test this next week and will let you know.