I have a Iphone with latest update installed. We will be travelling to Japan and normally I buy a sim card there and replace my German Telekom sim. Now I want to buy a esim, but I am somewhat apprehensive that some data will use the Telekom card and so causing a high bill.
What are my options:
1.Install the esim and take out the sim card. Easy, safe, but I might lose or damage my sim card.
2. Install the esim and disable the sim card. How do I disable the sim so it would not connect to the internet or receive sms?

Thanks