Mod Loader (Optional)

Forge

Minecraft Version(s) (Optional)

1.19.2

Mod Version(s) (Optional)

v4.0.2-1.19.2-Forge

Suggestion (Required)

Hi!

Please, check mod https://www.curseforge.com/minecraft/mc-mods/fence-on-slab. It visually extends the fence to reach the slab so no gap is there. I do not know yet well how it is working, but it seems it uses the resource pack for that. Please, check if that approach can be used to connect wall on the wall vertically just visually (not necessarily by additional block states).

Thanks!