Can I use a USB Wi-Fi adapter to extend a Wi-Fi connection on my MacBook I want to share an internet connection (Wi-Fi) through my laptop. I understand that you can't receive internet data and create a network simultaneously using the same internal adapter, but what if I bought a Wi-Fi adapter, like this one, so one can receive data and the other transmit it?
Yes

You can share/extend a network from Wi-Fi to Wi=Fi as long as you have two network adapters. In fact I am doing it right now!

I suggest you share Wi-Fi from the USB network adapter to the Internal Network Adapter, and not the other way around as it might cause issues (see pictures).

I would also suggest Panda Wireless PAU09 N600 Dual Band. I have used it with no problems. It works with Mac (Drivers needed), PC (Drivers needed), and Linux.  It's dual band, allowing you to connect to 5Ghz networks.  It support Monitor Mode, Packet Injection, and AP mode. The range is pretty good, would say about the same as the internal network adapter. It currently supports High Sierra and below. Heres the drivers download page.

Additionally, you can look at my answer over here for how to use your Mac as a router and change lease time, DHCP settings, DNS settings, Port Forwarding, etc.

Note:  Parts of the solution provided there (^^) does not constantly work.

Some pictures:




Note:  I am in no way affiliated with Panda Wireless, or the product the I suggested. I do not gain from the purchase of the product. I am not promoting the product, just suggesting it as an adapter that I have found works.