It does, I run it that way with an optional fan-out to my personal YaCy instance. Here's the relevant part of settings.yml:

   - name: yacy
     engine: yacy
     categories: general
     search_type: text
     base_url: https://yacy.searchlab.eu
     shortcut: ya
     disabled: true
     # required if you aren't using HTTPS for your local yacy instance
     # https://docs.searxng.org/dev/engines/online/yacy.html
     # enable_http: true
     # timeout: 3.0
     # search_mode: 'global'

Change 'disabled' to 'false' and point it at whatever YaCy instance you want to use. It can use the 'general' and 'images' categories.