Annoyingly, Firefox on Android lacks these options completely. You can't even control zoom for individual websites, it's all or nothing. It gets even worse on a foldable phone where you have two different displays. It's a bit off topic, but I am not aware of any browser that has reliable sync, working ad block, and per site zoom control on both Android and Windows.
Front-end developers: test your layouts in Firefox with "Zoom text only" set. It should work for all settings from 50% to 200%.