Well i think i found a solution for this: https://github.com/Itee/three-full/issues/12#issuecomment-433426345

this could be a example conifg:

{
  "compileOnSave": false,
  "compilerOptions": {
    "baseUrl": "./",
    "outDir": "./dist/out-tsc",
    "sourceMap": true,
    "declaration": false,
    "module": "es2015",
    "moduleResolution": "node",
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "importHelpers": true,
    "target": "es5",
    "typeRoots": [
      "node_modules/@types"
    ],
    "lib": [
      "es2018",
      "dom"
    ],
    "paths": {
      "three-full": ["node_modules/@types/three"]
    }
  }
}

then you should be able to import it like this:
import { LensFlareElement } from 'three-full';