Steps:

wget https://syncthing.net/release-key.gpg -O /etc/apt/trusted.gpg.d/syncthing-release.gpg
echo "deb https://apt.syncthing.net/ syncthing stable" > /etc/apt/sources.list.d/syncthing.list
printf "Package: *\nPin: origin apt.syncthing.net\nPin-Priority: 990\n" > /etc/apt/preferences.d/syncthing
apt update
apt full-upgrade -y
apt install syncthing -y

Create systemd service at system level (Default is user level)

#Add user for syncthing to operate on

#Copy existing service file for usermode as a b
mv /lib/systemd/system/syncthing@.service /lib/systemd/system/syncthing.service
nano /lib/systemd/system/syncthing.service