To expand on imobl’s spot-on reply:
To use a “SIM Box” analogy; the “box” inside your iPhone can hold at least 8 eSIMs electronically, along with one physical nanoSIM. (subject to important exceptions explained below)
Also note the subtle differences in terminology — eSIMs and nanoSIMs are both SIMs.
IPhone Xs/Xr and later are ALL capable of using up to TWO SIMs at one time. (This is what Apple means by “Dual SIM”)
iPhone Xs/Xr, 11, and 12 can use only ONE of the stored eSIMs at a time … alongside with up to one nanoSIM.
iPhone 13 and 14 can use any TWO of these eSIMs at a time … or up to one eSIM + one nanoSIM.
Important Exceptions:
- US iPhone 14s can’t use nanoSIMs at all.
- Chinese iPhones can’t use eSIMS at all (but can use 2x nanoSIMs)
Refs:
Using Dual SIM with an eSIM - Apple Support
About eSIM on iPhone - Apple Support