Disabling iPhone offloading to free up storage space

I'm quite often in low / no signal places so my iPhone is setup to have a lot of offline apps. I periodically have issues where my iPhone "helps" me by freeing up space. Unfortunately, a trigger can be downloading an offline map / wiki just before going somewhere without much coverage. I just turned off "offload unused apps" (and I'm not sure why it was on).

I'm wondering what other settings are lurking that are worth turning off. Any ideas?

(And there are probably better places to ask on the internet but I'm working to use a few less of the centralised sites or US tech.)