I could not figure out how to do this but i would like to have an option to allow adds on certain websites, some websites won’t allow me to use the page if don’t unblock all adds. Chrome extensions have this feature but i believe it would be better to be added in browser.
Click on the lion icon in the upper right and you can turn off the shield for ads & trackers.
You could also turn all shields off if you felt so inclined.
That will apply ONLY to the particular website you have open at that time.