The extensions to install:
- R (https://marketplace.visualstudio.com/items?itemName=Ikuyadeu.r)
- R LSP Client (https://marketplace.visualstudio.com/items?itemName=REditorSupport.r-lsp)
- R Tools (https://marketplace.visualstudio.com/items?itemName=Mikhail-Arkhipov.r)
For R LSP, you need to have R language server installed.