Turning ranking off

One switch replaces the ranked feed with a newest-first feed that does no scoring and no learning.

Two things do this, and they are not the same.

Following
The tab at the top of Home. Posts from accounts you follow, in time order, with no ranking applied. Switch back to For You at any time.
Algorithm off
The switch in Settings, then Feed. The whole feed becomes newest-first. Nothing is scored, and nothing is learned from what you do.

With the algorithm off, the ranking controls stay visible but stop having any effect, and the app says so on the settings screen rather than leaving you to guess.

What still applies

Blocks, mutes and the content comfort filters are not part of ranking, so they keep working with the algorithm off. Turning ranking off does not turn safety filtering off.