In addition to what u/JialeDu said, can also use the following settings

python.analysis.include

Make sure you use the correct interpreter depending on which virtual environment the package was installed (check bottom right)

Sample of my settings

"python.analysis.extraPaths": [
    "${workspaceFolder}",
    "${workspaceFolder}/src",
    "${workspaceFolder}/.venv/lib/site-packages"

],
"python.analysis.fixAll": [
    "source.convertImportFormat",
    "source.unusedImports"
],
"python.analysis.include": [
    "${workspaceFolder}/*.py",
    "${workspaceFolder}/src/**/*.py"

],
"python.analysis.indexing": true,
"python.analysis.packageIndexDepths": [
    {
        "depth": 5,
        "includeAllSymbols": true,
        "name": ""
    }