In Mac OS, the new System Settings controls how your Mac runs and behaives, some settings change users specific settings such as Desktop and Finder, while other affect the entire system. If a padlock icon appears in the bottom left of a preference window, then you will need Administrator rights to change those settings.
For example, if you wanted to change the Wallpaper you get the following
window with a list of possible settings.
Settings
Start Using iCloud - Access storage on Apple's iCloud with your Apple ID.
Wi-Fi - Configure wireless network access.
Bluetooth - Configure access to devices using Bluetooth.
Networks - Configure Ethernet, Wi-Fi (Wireless), Firewire, Blue tooth and network protocols.
Notifications - configure which alerts you want to see and how they are displayed.
Sound - Configure playback and recording devices, sounds effects, balance and volume.
Focus - Set 'Do not Disturb' option and whether sharing in available or not.
Screen Time - Monitor how much time spent with apps and set restrictions. See HT208982.
General - Set appearance, colour, scroll bars, browser and recent items.
AirDrop & Handoff - Airdrop to share with people nearby, AirPlay enable.
Login Items - Apps to open at login and which apps are allowed to run in background.
AppleCare & Warranty - Display infomration about AppleCare etc.
Language & Region - Set date and time formats, location, welcome screen settings and languages.
Date & Time - Configure local date and time settings, and the time zone.
Sharing - Enable sharing for files, web, login ftp, remote desktop, printers and so on.
Time Machine - Configure and start backups and restore of user data.
Transfer or Reset - Open Migration Assistant to transfer data and settings from another Mac or PC. Reset - option to erase on content and settings.
Startup Disk - Specify which disk or partition to boot from.
Appearance - Set Light or Dark mode, highlight colour, sidebar icon size, wallpaper tinting and scroll bars.
Accessibility - Manage ease of use tools and settings including Display, Zoom, Magnifier, On-Screen keyboard, Narrator, High Contrast.
Control Centre - Set when modules are visible in the Control Centre.
Siri & Spotlight - configure voice commands and speech. See Siri.Spotlight sets the sort order in which search results are ordered, keyboard shortcut
Privacy & Security - Set Password, app store security. Configure network protection against unauthorised access to your system. File Vault for file system encryption.
Desktop & Dock - Configure size, magnification, position, and animation of dock and icons..Set the desktop and Stage Manager iroms to show, recent items, wallpaper click etc
Displays - Configure monitor resolution and colour profile.
Wallpaper - Sets the wallpaper image for the desktop.
Screen Saver - Sets image for the screen saver.
Energy Saver - Set computer and display sleep settings, wake up options, brightness level and battery options.
Lock Screen - Settings for when lock screen show, show username, photo, hints or message when lockeds
Login Password - Change current user login password.
Users & Groups - Create, modify and delete user accounts, groups, login options, Directory Services.
Passwords - Display saved passwords and if to use Keychain for passwords. Clean up verification codes.
Internet Accounts - Setup accounts for iCloud, Exchange, Google, Twitter, Facebook etc.
Game Center - Enable game center for socal gaming with friends.
Wallet & Apple Pay - Manage boarding passes, tickets, coupons and rewards in one place. See HT204506.
Keyboard - Configure repeat delay, repeat rate, backlit, shortcuts, input sources and dictation for keyboard.
Mouse - Configure buttons, speed, zoom and other mouse options.
CDs and DVDs - Manage optical drives on Macs that have them attached.
Printers & Scanners - To manage peripherals such as scanners and printers.