When two SIMs are inserted:
You can specify which SIM to use for mobile data, calls, and text messages:
Select options:
Touch Mobile data and select a SIM.
You can also touch & hold
in quick settings to switch between SIMs for mobile data.
When two SIMs are inserted, you'll see them referenced in apps like Contacts, Messages, and Phone. To tell them apart more easily, change the default names (SIM1/SIM2) to more meaningful names. You can also change SIM icon color to make them easy to differentiate.
Change settings as needed: