Hello, Not sure this exists but hoping there is a solution. I have been getting a lot of fence objects that are rug based so sims keep walking through them. Is there something like an invisible object/tile or subtle ground decor like grass/rocks that can be placed where the fences are to block the sims walking through them?

Laphelot's Sim Solutions had non-walkable tiles in varing spaces. Of course, this site is dead now - but here's a link for those files:
https://drive.google.com/drive/fold...?usp=drive_link

There's more than just those files in the folder, btw.

It's also not difficult to edit the objects inside to remove that option.

Jendea had full-length windows that turned walls invisible as well... however, those do have the caveat that, being walls, they still produce wall-like visuals from some angles and settings (i.e. they look like walls when walls are down for instance) and can produce roofs. The current site has the entirety of each section in one zip each so without digging I'm not sure which object in the build zip(s) it might be: https://www.jendea.com/sims1jendea.html