Any way to "fake" having my phone turned off?

I’m looking for a way to make it seem like my Android phone is turned off without actually turning it off and without using airplane mode. Ideally:

• WhatsApp calls and videocalls shouldn’t go through
• WhatsApp messages should stay with a single checkmark on the sender side, as if the phone is off or out of service.

Is there a way to achieve this without physically turning off the phone? Maybe some settings or a specific mode? Any advice is appreciated!

The reason I’m asking is that I rarely use WhatsApp, and I don’t want to be disturbed. However, I still want to be able to make calls, browse the internet, use other messaging apps, and so on.
I’d like to be the one who decides when people can reach me on Whatsapp, and I also want to discourage people from contacting me in the first place.

EDIT: clarifications