fix: correct accountLinking default to true (#6963)

Co-authored-by: Alex Yang <himself65@outlook.com>

docs/content/docs/reference/options.mdx

@@ -420,7 +420,7 @@ Store account data after OAuth flow in a cookie. This is useful for database-les
 
 Configuration for account linking.
 
-- `enabled`: Enable account linking (default: `false`)
+- `enabled`: Enable account linking (default: `true`)
 - `trustedProviders`: List of trusted providers
 - `allowDifferentEmails`: Allow users to link accounts with different email addresses
 - `allowUnlinkingAll`: Allow users to unlink all accounts

packages/better-auth/src/plugins/one-tap/index.ts

@@ -148,8 +148,8 @@ export const oneTap = (options?: OneTapOptions | undefined) =>
 					if (!account) {
 						const accountLinking = ctx.context.options.account?.accountLinking;
 						const shouldLinkAccount =
-							accountLinking?.enabled &&
-							(accountLinking.trustedProviders?.includes("google") ||
+							accountLinking?.enabled !== false &&
+							(accountLinking?.trustedProviders?.includes("google") ||
 								email_verified);
 						if (shouldLinkAccount) {
 							await ctx.context.internalAdapter.linkAccount({