Step1. Update current distribution
apt update
apt upgrade -y
apt full-upgrade -y
apt autoclean
apt autoremove -y
Step2. Change repo to trixie, from bookworm.
sudo sed -i 's/bookworm/trixie/g' /etc/apt/sources.list
Change all 3rd-party repos
sudo find /etc/apt/sources.list.d -type f -exec sed -i 's/bookworm/trixie/g' {} \;
Step3. Update Debian
apt update
apt upgrade -y
apt full-upgrade -y
Step4. Clean up old repos
apt autoclean
apt autoremove -y
Step5. Reboot
reboot