https://wiki.postgresql.org/wiki/Apt
https://www.tecmint.com/install-postgresql-on-debian-and-ubuntu/

https://www.postgresql.org/download/linux/debian/ - здесь САМ Postgres пишет как его установить

1. File /etc/apt/sources.list.d/pgdg.list

sudo sh -c 'echo "deb http://apt.postgresql.org/pub/repos/apt $(lsb_release -cs)-pgdg main" > /etc/apt/sources.list.d/pgdg.list'
#--------------- On Buster 10.x ---------------
#deb http://apt.postgresql.org/pub/repos/apt/ buster-pgdg main
#--------------- On Stretch 9.x ---------------
#deb http://apt.postgresql.org/pub/repos/apt/ stretch-pgdg main
#--------------- On Jessie 8.x ---------------
#deb http://apt.postgresql.org/pub/repos/apt/ jessie-pgdg main
#--------------- On Wheezy 7.x ---------------
#deb http://apt.postgresql.org/pub/repos/apt/ wheezy-pgdg main

2. Import the repository key from https://www.postgresql.org/media/keys/ACCC4CF8.asc

# sudo apt-get install curl ca-certificates gnupg
# curl https://www.postgresql.org/media/keys/ACCC4CF8.asc | sudo apt-key add -
# sudo apt update

или

# sudo apt-get install wget ca-certificates gnupg
# wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | sudo apt-key add -
# sudo apt update

3.

# apt install postgresql-9.5
# apt install postgresql-9.6
# apt install postgresql-10
# apt install postgresql-11
# apt install postgresql-12