Somewhere on a train platform in Porto, someone's laptop needs the internet and your phone is the only device with a signal. This is the entire use case for a hotspot, and the good news is a travel eSIM handles it exactly the way your home SIM does - because as far as your phone's data connection is concerned, there's no difference between a browser tab and a laptop borrowing the connection.
How it actually works
A travel eSIM is a data line, full stop, and hotspotting is just sharing that data line with another device over Wi-Fi, Bluetooth, or a cable. Turn on Personal Hotspot (iPhone) or Hotspot & tethering (Android), set a network name and password if you haven't already, and any laptop, tablet or second phone nearby can join it like any other Wi-Fi network. Your travel eSIM doesn't know or care that the request came from a laptop rather than your own screen.
There's no separate setting to enable hotspotting for a travel line specifically - if mobile data is working on the phone at all, the hotspot works too. The only thing worth checking first is that Data Roaming is switched on for the travel eSIM, the same toggle that governs everything else about the line; without it, neither your phone nor anything tethered to it will get online.
What can actually join
Anything that connects to a normal Wi-Fi network can join your hotspot - a laptop, a tablet, an e-reader, a second phone belonging to whoever you're travelling with. There's no device allowlist and no separate fee for tethering itself; the connection is treated as ordinary data use by whichever device is asking for it. Worth knowing too: running a hotspot for hours at a time draws down your phone's battery noticeably faster than normal browsing, so a charger or a power bank is a sensible companion to a long working session on a train.
The one thing that changes: the maths
What's different isn't whether hotspotting works, but how fast it spends your data. A laptop pulling emails and a few browser tabs is modest. A laptop syncing photos, streaming a call, or updating software in the background is not, and it will draw down a travel bundle considerably faster than the phone alone ever would - often within a single working session.