The number of eSIM profiles that can be stored at once depends on the device hardware and software limitations. This can vary by the region of manufacture for a single device model.
Some devices will only allow for a single eSIM, others will allow for as many as you would like. If you are able to install many eSIM some devices may only allow for one to be activated and used at any one time, where as other may allow for the use of many with options to choose what to use when requesting voice, SMS, or data services from your device.