I realize there are other similar threads, but they haven't helped me.
My graphics card is simply listed as 'Intel(R) UHD Graphics'. It is updated. My computer is a Lenovo Thinkpad with CORE i7 vPRO (10th gen).
There is an HDMI port and a USB -C port (and other USB 3.2 ports). My 2 monitors will work directly through the HDMI port or through a USB-C to HDMI port adapter, but both monitors will not work at the same time (eg., when one is plugged into the HDMI port and the other is plugged into the USB-C adapter).
Is there some way to use 2 monitors (preferably with extended desktop)?
You really need to be talking to Lenovo about this. It sounds like the two connectors are using the same DisplayPort channel. If that's the case, then you can only use one of these connectors.
Now, you cannot connect two monitors via the HDMI connector, but you may be able to do so via the USB-C connector if they haven't screwed it up (or the processor is not too old). For example, you may be able to connect two HDMI monitors using an MST hub device like this: https://www.amazon.com/dp/B07QKVY23Q.
Hope this helps,