不知道lang选项，但可以在YAML中设置用于图和表标题的prefix。（注意：还有几个选项。参见?officedown::rdocx_document）

---
date: "`r Sys.Date()`"
author: "Your Name"
title: "officedown template"
output: 
  officedown::rdocx_document:
    tables:
      caption:
        pre: 'Tabelle'
    plots:
      caption:
        pre: 'Abbildung'
      topcaption: true
---
```{r setup, include=FALSE}
library(officedown)
library(ggplot2)

Figure

ggplot(economics, aes(date, unemploy / pop)) + 
  geom_line() + 
  theme_minimal()

Table

head(economics)

字符串
![](https://i.stack.imgur.com/mFQ0p.png)
的数据