To get event data, you can use a GitHub action to print the event to the log.

# change this to the event type you want to get the data for
on:
  pull_request:
    types: [opened, closed, reopened]

jobs:
  printJob:    
    name: Print event
    runs-on: ubuntu-latest
    steps:
    - name: Dump GitHub context
      env:
        GITHUB_CONTEXT: ${{ toJson(github) }}
      run: |
        echo "$GITHUB_CONTEXT"

Alternatively, you can find example event data in the documentation: https://docs.github.com/en/developers/webhooks-and-events/webhook-events-and-payloads#webhook-payload-example-30

The GitHub API provides no way to retrieve a particular event by its ID.

Each event has a payload inside of it. For example

{
    "actor": {
        "avatar_url": "https://avatars.githubusercontent.com/u/240830?",
        "display_login": "sigmavirus24",
        "gravatar_id": "",
        "id": 240830,
        "login": "sigmavirus24",
        "url": "https://api.github.com/users/sigmavirus24"
    },
    "created_at": "2017-01-27T23:50:12Z",
    "id": "5227100855",
    "org": {
        "avatar_url": "https://avatars.githubusercontent.com/u/1782156?",
        "gravatar_id": "",
        "id": 1782156,
        "login": "github3py",
        "url": "https://api.github.com/orgs/github3py"
    },
    "payload": {
        "before": "7d52c200d80d86f70fbda3e9ebf48060867f9f65",
        "commits": [
            {
                "author": {
                    "email": "[email protected]",
                    "name": "Ian Cordasco"
                },
                "distinct": true,
                "message": "Create test.txt",
                "sha": "a623ca5974523ec35fd83909dd99b220e498ef58",
                "url": "https://api.github.com/repos/github3py/delete_contents/commits/a623ca5974523ec35fd83909dd99b220e498ef58"
            }
        ],
        "distinct_size": 1,
        "head": "a623ca5974523ec35fd83909dd99b220e498ef58",
        "push_id": 1525269783,
        "ref": "refs/heads/master",
        "size": 1
    },
    "public": true,
    "repo": {
        "id": 50486230,
        "name": "github3py/delete_contents",
        "url": "https://api.github.com/repos/github3py/delete_contents"
    },
    "type": "PushEvent"
}

Is an event from a list after doing GET /orgs/github3py/events. If you look closely you'll see

    "payload": {
        "before": "7d52c200d80d86f70fbda3e9ebf48060867f9f65",
        "commits": [
            {
                "author": {
                    "email": "[email protected]",
                    "name": "Ian Cordasco"
                },
                "distinct": true,
                "message": "Create test.txt",
                "sha": "a623ca5974523ec35fd83909dd99b220e498ef58",
                "url": "https://api.github.com/repos/github3py/delete_contents/commits/a623ca5974523ec35fd83909dd99b220e498ef58"
            }
        ],
        "distinct_size": 1,
        "head": "a623ca5974523ec35fd83909dd99b220e498ef58",
        "push_id": 1525269783,
        "ref": "refs/heads/master",
        "size": 1
    },

Which is the payload from the event. That's the only way to get that payload (from listing events).