Previously, on Amazon Linux 2, which was based on CentOs, you could add an Epel-Release repository and then install the corresponding package. On Amazon Linux 2023 this is not possible, as it is a Fedora-based OS, so Epel-Release is not supported. Here is a short article on the topic: https://linux.how2shout.com/can-we-install-epel-repo-on-amazon-linux-2023/.
However, this does not mean that installing the right package is not possible. One solution might be to use rpmfind.net to find a repository where the package of your choice is available. Take a look at https://rpmfind.net/linux/rpm2html/search.php?query=rabbitmq-server, for example. This way you can find the right RPM repository and try to install it using commands:
dnf config-manager --add-repo some-url/repository.repo
dnf config-manager --set-enabled some-repository
The second possible solution is to install the selected package using the URL:
dnf install -y https://rpmfind.net/linux/fedora/linux/releases/38/Everything/x86_64/os/Packages/r/rabbitmq-server-3.11.10-1.fc38.x86_64.rpm
Note, however, that for security reasons it is best to use the official repositories.