Einstellen während der Installation

https://github.com/QuietWorry/Pi5-Mainsail

Click "Next" on RPI Imager
Click "Edit Settings"
Enable "Set hostname" and change hostname as desired
Set Username and password
If using WiFi: Enable and set SSID and Password for your network, then select correct country
Enable and set locale settings
Navigate to "Services" tab and enable SSH with password authentication (or pub-key authentication)
Click "Save" at the bottom
Click "yes" to apply OS customization settings
Click "yes" to erase all data on SD if prompted
Wait for OS to write and verify
Safely remove SD and install on Pi 5

Shell:

login in to your Pi via SSh

read hostname

$ hostname
raspberry

change hostname
$ sudo hostnamectl set-hostname

sudoedit /etc/hosts

to change 

https://linuxconfig.org/how-to-set-hostname-on-raspberry-pi