How to get current WiFi signal strength?
You use WiFi.RSSI():

RSSI
Return the signal strength of Wi-Fi network, that is formally called Received Signal Strength Indication (RSSI).
WiFi.RSSI()

Signal strength value is provided in dBm. The type of returned value is int32_t.
Example code:
Serial.printf(&quot;RSSI: %d dBm\n&quot;, WiFi.RSSI());

Example output:
RSSI: -68 dBm