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