The Sony Xperia M5 requires a nano-SIM card
This uses the Sony Xperia M5 a Sim card type which is more and more popular because it currently has the smallest format of all variants.
Option 1: Sim card punch
With a Sim card punch you can punch out a Nano-SIM card from a standard or micro-SIM card. These templates are included, which then corresponds to the format of the nano-Sim.
Such Sim Card Punching there are, for example, on Amazon
Request Nano Sim Card at Mobile operators: Option 2
Of course your mobile operator sends you to a nano sim card. This comes at a cost of € 10-25 (depending on your network provider).
You know now that the new Sony Xperia smartphone requires M5 Sim card format.