Wiki等のものをコピペしても動かなかったので調べました．

設定

settings.json に以下のものを追加します．

"latex-workshop.view.pdf.viewer": "external",
"latex-workshop.view.pdf.external.viewer.command": 
        "C:\\(pathが入る)\\Local\\SumatraPDF\\SumatraPDF.exe",
"latex-workshop.view.pdf.external.viewer.args": [
        "-reuse-instance",
        "%PDF%"
],
"latex-workshop.view.pdf.external.synctex.command": 
        "C:\\(pathが入る)\\SumatraPDF\\SumatraPDF.exe",
"latex-workshop.view.pdf.external.synctex.args": [
        "-reuse-instance",
        "-forward-search",
        "%TEX%",
        "%LINE%",
        "%PDF%"
],

これでforward searchとpdfの表示ができました．inverse searchはTeX Wikiのもので動きました．
参照：
James-Yu/LaTeX-Workshop View
https://github.com/James-Yu/LaTeX-Workshop/wiki/View,
TeX Wiki : SumatraPDF との synctex 連携
https://texwiki.texjp.org/?Visual%20Studio%20Code%2FLaTeX#g142ea7e

LaTeX WorkshopでSumatraPDFを使う

設定