@PJCA
The Archer AX55 (and also most other TP-Link routers) won't display any technical details about the Wi-Fi connection of connected client devices.
I currently don't own any iOS devices and therefore can't check this myself, but I guess iOS doesn't show the information you are looking for either.
Your best bet might be to try out some free "system info" or "Wi-Fi info" apps that are specially made to show detailed information about the user's device.
For a start maybe try "AIDA64".
In case whatever app you try doesn't show the specific wireless standard, you still might be able to derive it by the so called "link speed". Numbers like 433, 866 or 1733 Mbps usually indicate a Wi-Fi 5 connection, whereas 600, 1200 or 2400 Mbps would likely indicate a Wi-Fi 6 connection.