It would be great if every IoT device deployed with OTA capability with Wifimanager. Then, your IoT device would be able to change SSID & Password without re-upload firmware as well as FOTA at any time when you wanted.
Why did I use the ESPAsync_WiFiManager library? It's because WiFiManager does not work with AsyncElegnatOTA together. You have to change to ESPAsync_WiFiManager. The main reason for this is that AsnycWiFiManager is using Asynchronous technology. Which means it can accept connections from different sources at the same time. So, while ESPAsyncWiFiManager is running on the IoT device, the device can also be a FOTA server to allow firmware to be remotely updated in the future!
If you are interested, please visit the blog for a YouTube video and the code I used for both ESP32 & ESP8266. https://stonez56.blogspot.com/2021/07/asyncwifimanager-elegantota-esp32-wifi.html?fbclid=IwAR0D_0jAJ7CLx5iUddg2EZ6sd1AC_OxeF5riivfaUJ8U5iUOQeNAnMNf72U