Step 1: Go to

Step 2: Right click on the address bar.

Step 3: Select ‘Add “perplexity open search”’

Now you can select perplexity in Firefox settings.

Step 4: Go to about:preferences#search, and under “Default Search Engine” select “perplexity”.

Note: instead of setting Perplexity as the default search engine, creating a shortcut for it might be preferred.