Tethering works on metered plans. On unlimited plans for some destinations it is not included, and that is always stated on the plan page before you buy.
How to turn it on
On iPhone: Settings > Personal Hotspot > on. With multiple lines, check that mobile data is set to the eSIM line.
On Android: Settings > Connections or Network & internet > Mobile hotspot.
Why a laptop uses so much
A laptop does things in the background a phone does not: system updates, cloud sync, open tabs refreshing themselves. A couple of hours of work eating a gigabyte is not unusual.
Before you tether a laptop:
- pause system updates,
- turn off syncing of large folders,
- switch the camera off in video calls when it is not needed.
What size plan to take if you tether
If you plan to work from a laptop, budget at least 1.5 GB per working day. For a week that means a 10 GB plan or larger.