How do I bridge a wifi connection from MacOS
I assume your question is how to share the WiFi internet connection you have with other devices on a cabled network.

You do this by opening System Prefences > Sharing and selecting Internet Sharing:

For "Share your connection from" choose "Wi-Fi".

For "To computers using" select the network that you want to share it with - usually this is "Ethernet".

This achieves connection sharing by using NAT.

If you actually want to bridge your WiFi connection with a cabled connection, so that devices on your cabled connection would work like they were connected directly to the WiFi, it can be achieved like this:

Open System Preferences > Network. 

Click the cog wheel below the device list and select "Manage Virtual Interfaces". 

Click the plus button and select "New Bridge".  

Select "Wi-Fi" and the network you want to share it with - usually this is "Ethernet".

Click Create.