Just saw the recent updated and installed, however it appears the renderPreview option is no where to be found? I've looked in the mod settings through modmenu and through settings of litematica itself.

Using..
Minecraft 1.21.4
Fabric-loader 0.16.10
fabric-api 0.118
modmenu 13.0.2
owo lib0.12.20
isometric Renders 0.4.9
malilib 0.23.2
litematica 0.21.2
Techutils 0.5.3

Doh. I had been looking at that other mod as well. Thanks!

In 1.21.4 and above the Litematica Render Preview feature has been removed due to its maintenance cost. Fortunately tho, there is a new mod which provides basically the same functionality. Check out SchematicPreview - https://modrinth.com/mod/schematicpreview