App to change the Code

hi I have two questions. I am currently programming an esp 8266 d1 mini and I wanted to ask if it is possible, for example, to change the wlan network and password on the smartphone.
2nd I wanted to ask if you can make a website in which you have a small button that you can change with the PC / Smartphone and the esp displays.
Thank you for asking.

burdicojr: I wanted to ask if it is possible, for example, to change the wlan network and password on the smartphone.

Yes. You might find this library useful for that purpose: https://github.com/tzapu/WiFiManager

burdicojr: I wanted to ask if you can make a website in which you have a small button that you can change with the PC / Smartphone and the esp displays.

Yes, it's possible. The example sketches under File > Examples > ESP8266WebServer should get you started.