dnf in tftp-server firewall-cmd --add-service=tftp systemctl start tftp.socket
if you want to make it permanent instead:
firewall-cmd --permanent --zone=home --add-service=tftp firewall-cmd --reload systemctl enable tftp.socket systemctl daemon-reload
if you only want to bind to a specific IP/port:
… [Service] ExecStart=/usr/sbin/in.tftpd -s /var/lib/tftpboot -a 127.0.0.1:69 …