A container is not a virtual machine so you can’t use it like that. Systemd is something that runs as the very first process on top of a Linux kernel to handle all the other processes in most of the modern Linux distributions, but not in an application container which is an isolated environment for a process and not an entire operating system.
If you want something that allows you to install almost everything as you would do on a physical machine or in a virtual machine, you can try “system containers”. Docker is for application containers. LXD and Incus are for system containers.
In a Docker container you (almost always) run processes without Systemd. If you need multiple processes in a single container, you can try Supervisor or s6-init for example.
If you want to know why you should not use Systemd in a Docker container, you can search for systemd on the forum, or read my tutorial that includes systemd as well
I never tried, but Podman claims to be able to run Systemd more easily
What exactly do you want to run in a container? You can use a base image which already contains what you need and built for starting the process properly.