findNestedObject.js

function findNestedObject(object, keyToFind, valToFind) {
	let foundObj;
	JSON.stringify(object, (_, nestedValue) => {
		if (nestedValue && nestedValue[keyToFind] === valToFind) {
			foundObj = nestedValue;
		}
		return nestedValue;
	});
	return foundObj;
}

update.js

const object = {
	schemaVersion: 15,
	body: {
		id: "cnWNPmSTDG",
		rows: [
			{
				id: "tyrtnyEeRX",
				columns: [
					{
						id: "oswmB3BZoE",
						contents: [
							{
								id: "L_YoZhqJ7L",
								type: "heading",
								values: {
									fontSize: "22px",
									linkStyle: {
										linkColor: "#0000ee"
									},
									displayCondition: null
								}
							},
							{
								id: "XHWYbiN6Su",
								type: "form",
								values: {
									action: {
										method: "POST",
										url: "https://mailbluster.com"
									},
									fields: [
										{
											name: "email",
											label: "Email address",
											type: "email",
											required: true
										},
										{
											type: "checkbox",
											name: "consent",
											label: "Consent",
											required: true
										}
									]
								}
							}
						]
					}
				]
			}
		]
	}
}

findNestedObject(object, "type", "checkbox");

// expected output
// 
//   {
//     type: 'checkbox',
//     name: 'consent',
//     label: 'Consent',
//     options: 'I agree to your terms and condition',
//     placeholder_text: 'Consent',
//     show_label: false,
//     required: true,
//     meta_data: {}
//   }