On my Sprint Galaxy S7 there was a symbol on the status bar if I was actually connected to wifi calling, I just upgraded to the S10 on T-Mobile, which so far is much better, however I have no cell service at my job (steel building) and must always know that my wifi calling is connected. I know that I can check to see if wifi calling is actually turned on, but not if there is actual connection.
Unfortunately, that's a change that was made with Android 9. There won't be an icon up at the top with any of the newer Android devices because that's a change having to do with the software, not the hardware of the device.
You should be able to pull the bar down to see status, and if it indicates connected, it's the equivalent of the icon.