Thanks for replying, PhoenixAshes136, and that additional info, it really helps! You may need to reset NVRAM if this is an older Mac with an Intel process: What to do before you sell, give away, or trade in your Mac - Apple Support
Also, looking at this Apple resource, you may not be using the correct keys during startup:
"On an Intel-based Mac, you can use Shift-Option-Command-R during startup to be offered the macOS that came with your Mac, or the closest version still available. Or you can use Option-Command-R during startup to be offered either the latest macOS that is compatible with your Mac, or in some cases the macOS that came with your Mac or the closest version still available."
How to reinstall macOS - Apple Support
Have a great day and thanks for using the Apple Support Communities!