Unfortunately, it is not possible to add eSIM functionality to a phone that does not already have eSIM support built-in. eSIM (embedded SIM) technology requires specific hardware and software support within the phone itself.
If your phone does not have eSIM support, you will not be able to use eSIM functionality on that device. In this case, your options would be to either use a physical SIM card or consider upgrading to a phone that supports eSIM if you wish to take advantage of eSIM technology.