Setting up emacs from scratch

init.el

;; melpa
(require 'package)
(add-to-list 'package-archives '("melpa" . "https://melpa.org/packages/") t)
(package-initialize)

;; package installation and configuration
(use-package olivetti
  :ensure t)

(use-package exotica-theme
  :ensure t)

;; the rest...
(defun my/initial-layout ()
  "Create my initial screen layout."
  (interactive)
  ;; 1. to have exotica theme mode enabled, along with
  (load-theme 'exotica t)
  ;; 2. having org-mode launch in scratch buffer from the beginning, and
  (switch-to-buffer "*scratch*")
  (org-mode)
  (org-indent-mode)
  ;; 3. to have olivetti mode enabled too.
  (olivetti-mode)
  (delete-other-windows)
  )

(my/initial-layout)

;; Everything below this was added by emacs.

(custom-set-variables
 ;; custom-set-variables was added by Custom.
 ;; If you edit it by hand, you could mess it up, so be careful.
 ;; Your init file should contain only one such instance.
 ;; If there is more than one, they won't work right.
 '(inhibit-startup-screen t)
 '(package-selected-packages '(exotica-theme use-package olivetti)))
(custom-set-faces
 ;; custom-set-faces was added by Custom.
 ;; If you edit it by hand, you could mess it up, so be careful.
 ;; Your init file should contain only one such instance.
 ;; If there is more than one, they won't work right.
 )

MELPA and use-package

The first thing I did was create ~/.emacs.d/init.el and setup MELPA which lets me install more packages.

;; melpa
(require 'package)
(add-to-list 'package-archives '("melpa" . "https://melpa.org/packages/") t)
(package-initialize)

This let me use M-x package-install to install use-package. Once that's installed, I can install packages with use-package declarations.

;; package installation and configuration
(use-package olivetti
  :ensure t)

(use-package exotica-theme
  :ensure t)

Configuration

With all the prerequisites installed, I was able to finish writing a config that would solve this question on emacs.stackexchange.org.

;; the rest...
(defun my/initial-layout ()
  "Create my initial screen layout."
  (interactive)
  ;; 1. to have exotica theme mode enabled, along with
  (load-theme 'exotica t)
  ;; 2. having org-mode launch in scratch buffer from the beginning, and
  (switch-to-buffer "*scratch*")
  (org-mode)
  (org-indent-mode)
  ;; 3. to have olivetti mode enabled too.
  (olivetti-mode)
  (delete-other-windows)
  )

(my/initial-layout)

The end result looks like this: