If your Paca is connected to a network that has a DHCP server active then it receives it IP address from the DHCP service. Most Wi-Fi access points and other router include a DHCP server. Usually these have an option to assign a specific IP address to a particular device. Check your router manual for details how to do this.
If the Paca is connected only to your computer then it will "self-assign" its IP address, unless the computer is running a DHCP process; that, however is unusual and requires customizing your Windows or MacOS set up to include a DHCP server function.
If you are using a Mac, and running KymaConnect, then you can achieve the effect of the Paca having a fixed IP address by interacting with the Paca through KymaConnect's "PacaProxy" feature. In this case the IP address is the IP address of the Mac running KymaConnect. You can assign a fixed IP address to the Mac's network port that you use to connect to the PacaProxy (usually the Wi Fi interface) using System Preferences:Network. Or have the network interface get its IP address using DHCP and set up your network's DHCP service to provide the same IP address to the Mac, just as described above.