How to execute commands when starting ubuntu 20.04?

Question

ubuntu

I'm new to Ubuntu, but in general I'm familiar with the terminal, I googled different options, but they don't work.
Basically, it says you need to execute commands through rc.local , but as I understand it, it doesn't exist in 20.04, even 18.04 didn't exist, or maybe I'm not right)
in any case, tell me the latest information on how to execute commands at system startup?
I need to mount disks, run programs and a couple more console commands

Answer 1

mount disks - edit /etc/fstab , configure autofs service to
run programs, and execute commands - add scripts to cron, @reboot event.
Like this:
@reboot /usr/loca/bin/startup.sh > /var/log/startup.log

Answer 2

stationary disk mounting is written in /etc/fstab
running commands myunit.service + myunit.timer for me so the torrent daemon starts five minutes after downloading.
launching a program with a graphical interface, see the options of your desktop.