The most recent WhatsApp beta for Android, version 2.24.18.14, introduces an interesting new feature: managing contact syncing. This works with the upcoming ability to use multiple WhatsApp accounts on the same phone.
It will let you have separate contacts for each account. You’ll be able to choose which contacts to sync to your phone, and manage WhatsApp contacts from your linked devices. So, if you want to, you’ll be able to disable syncing to your phone from your secondary WhatsApp account.
Interestingly, even if you disable contact syncing for an account, you will still be able to manually sync each contact with an upcoming beta release. Manually syncing a contact will make it available across all linked devices. There will also be a new contact backup option, which will let you restore your contacts if you reinstall the app.
As always with WhatsApp features that are in development, expect at least a few months to pass before this is made available to everyone.