Apologies if this doesn’t fit here, not sure where else to post something like this on lemmy
I think having gravity act like weather might be an interesting concept for a fantasy world, where each country has its own gravity patterns, some tend to be heavier some tend to be lighter, some are all over the place
For a few examples, there could be a desert with gravity so high you can get dragged down into the sand
Could be a country with gravity so low everyone uses personal aircraft that work like bicycles instead of land vehicles
Animals in higher gravity areas would have less dense bones, more muscle, etc and lower gravity would have far larger animals because they can support more weight
In a really high gravity area people might need exoskeletons to prevent long term damage
https://gpg.geosci.xyz/content/gravity/gravity_basics.html
If for some reason the whole planet were made of a less dense material except underneath my house was a massive deposit of gold or lead or something, yes, in reality, that variation in gravity can be measured.
https://bigthink.com/strange-maps/indian-ocean-gravity-hole/
Further reading.
Obviously in your fictional world there has to be a reason tiny anomalies are amped up to eleven. But yes, geology drives gravity variations.
I think the way I’d do it if I were writing a story about this world would be to just not mention the technicalities
Either it’s a medieval level fantasy world where they don’t understand how it works and it’s equivalent to how the sun works or weather works
Or it’s modern day and people generally don’t talk about the finer technicalities the same way people don’t go around casually discussing in detail what causes wind to blow or temperatures to rise and fall
Also, it’s fantasy so it could also just be it works that way because all poweful space cthulu decided that’s how it works
I don’t think your readers would just except that gravity is just smudged across the planet. Sure, some fantasy has iffy rules and little explanation, but something like this smacks more of high fantasy or even scifi.
You don’t need to have a geologist character boring your characters, but some level of lore explaining folke reasons for the variation is going to color your world and sell it.
It will absolutely help to have some hint at an explanation
But if the world is not at the the technological level required to figure it out then it wouldn’t make any sense for them to explain it scientifically
They could perhaps explain it as it is this way because the gods made it this way, or because it’s fantasy it actually could be because the gods made it that way (hence my magic space cthulu comment)