My suggestion is to go online and look for the applicable User Guides/Manuals.
Read carefully, especially the fine print.
Check the applicable product FAQs and Forums - you are likely to find out more about it all and what does or does not really work.
More information:
https://www.canstarblue.com.au/phone/esim-plans-providers/
Found this about T-Mobile:
https://support.t-mobile.com/thread/147928
Details matter.