eSIMs are sold with data bundles only. This means that no phone number is supplied with the eSIM, meaning that voice and SMS cannot be used with the eSIM as no phone number is assigned to them.
It is however possible to have multiple eSIM installed, as well as a plastic SIM, to provide multiple options for managing eSIMs and the bundles being used. For example, it is possible to have many eSIMs each with different data bundles applied for use in different regions or destinations. Conversely, it is also possible to queue multiple bundles against a single eSIM.
With being able to use an eSIM alongside a traditional plastic SIM it allows for the use of data roaming services through the eSIM and to be able to continue to use your current SIM card providers services. Your plastic SIM, or your primary SIM, will be able to do roaming for voice and SMS. It will however be subject to your carriers rates and fees for roaming.
To be able to continue to use your number over data services it would require binding to a data based telephony service such as WhatsApp. This will then mean that you will avoid any roaming charges for voice and SMS whilst using the data on your eSIM for keeping in contact with those you need to.