Spreadsheets, driven by code.

<?php

require 'vendor/autoload.php';

use Google\Client;
use Google\Service\Sheets;
use Google\Service\Sheets\BatchUpdateSpreadsheetRequest;
use Google\Service\Sheets\Request;
use Google\Service\Sheets\ValueRange;

$spreadsheetId = 'YOUR_SPREADSHEET_ID';
$keyFile = 'service-account.json';
$tabName = 'Sales';

$client = new Client();
$client->setApplicationName('Format Google Sheets Cells');
$client->setAuthConfig($keyFile);
$client->addScope(Sheets::SPREADSHEETS);

$service = new Sheets($client);

/**
 * Return the numeric sheetId for a tab name, creating the tab if needed.
 */
function sheetIdFor(Sheets $service, string $spreadsheetId, string $title): int
{
    foreach ($service->spreadsheets->get($spreadsheetId)->getSheets() as $sheet) {
        if ($sheet->getProperties()->getTitle() === $title) {
            return $sheet->getProperties()->getSheetId();
        }
    }

    $service->spreadsheets->batchUpdate($spreadsheetId, new BatchUpdateSpreadsheetRequest([
        'requests' => [
            new Request(['addSheet' => ['properties' => ['title' => $title]]]),
        ],
    ]));

    return sheetIdFor($service, $spreadsheetId, $title);
}

$sheetId = sheetIdFor($service, $spreadsheetId, $tabName);

$service->spreadsheets_values->update(
    $spreadsheetId,
    $tabName . '!A1',
    new ValueRange(['values' => [
        ['Item', 'Qty', 'Price'],
        ['Widget', 120, 9.99],
        ['Gadget', 45, 24.50],
        ['Doohick', 300, 1.75],
    ]]),
    ['valueInputOption' => 'USER_ENTERED']
);

$headerFormat = new Request(['repeatCell' => [
    'range' => [
        'sheetId'          => $sheetId,
        'startRowIndex'    => 0,
        'endRowIndex'      => 1,
        'startColumnIndex' => 0,
        'endColumnIndex'   => 3,
    ],
    'cell' => ['userEnteredFormat' => [
        'backgroundColor'     => ['red' => 0.20, 'green' => 0.36, 'blue' => 0.00],
        'horizontalAlignment' => 'CENTER',
        'textFormat'          => [
            'bold'            => true,
            'fontSize'        => 12,
            'foregroundColor' => ['red' => 1.0, 'green' => 1.0, 'blue' => 1.0],
        ],
    ]],
    'fields' => 'userEnteredFormat(backgroundColor,horizontalAlignment,textFormat)',
]]);

$priceFormat = new Request(['repeatCell' => [
    'range' => [
        'sheetId'          => $sheetId,
        'startRowIndex'    => 1,
        'endRowIndex'      => 4,
        'startColumnIndex' => 2,
        'endColumnIndex'   => 3,
    ],
    'cell' => ['userEnteredFormat' => [
        'numberFormat' => ['type' => 'CURRENCY', 'pattern' => '"$"#,##0.00'],
    ]],
    'fields' => 'userEnteredFormat.numberFormat',
]]);

$service->spreadsheets->batchUpdate($spreadsheetId, new BatchUpdateSpreadsheetRequest([
    'requests' => [$headerFormat, $priceFormat],
]));

echo "Formatting applied.\n\n";

$meta = $service->spreadsheets->get($spreadsheetId, [
    'ranges'          => [$tabName . '!A1'],
    'includeGridData' => true,
    'fields'          => 'sheets(data(rowData(values(userEnteredFormat))))',
]);

$format = $meta->getSheets()[0]->getData()[0]->getRowData()[0]->getValues()[0]->getUserEnteredFormat();
$text = $format->getTextFormat();
$fill = $format->getBackgroundColor();

echo "A1 as the spreadsheet now stores it:\n";
printf("  bold       : %s\n", $text->getBold() ? 'yes' : 'no');
printf("  font size  : %s\n", $text->getFontSize());
printf("  text colour: %.2f / %.2f / %.2f\n",
    $text->getForegroundColor()->getRed() ?? 0,
    $text->getForegroundColor()->getGreen() ?? 0,
    $text->getForegroundColor()->getBlue() ?? 0);
printf("  fill colour: %.2f / %.2f / %.2f\n",
    $fill->getRed() ?? 0, $fill->getGreen() ?? 0, $fill->getBlue() ?? 0);
printf("  alignment  : %s\n", $format->getHorizontalAlignment());

$prices = $service->spreadsheets_values->get($spreadsheetId, $tabName . '!C2:C4', [
    'valueRenderOption' => 'FORMATTED_VALUE',
])->getValues();

echo "\nPrice column as displayed:\n";
foreach ($prices as $row) {
    printf("  %s\n", $row[0]);
}