I signed a contract for the sale of second-hand houses, but now can I check that the tiles on the outer wall of the house have fallen off? Is it a breach of contract?

You bought a second-hand house. You didn't drop the tile when you signed the contract, only later. Ceramic tiles are the responsibility of the developer, not the second-hand house landlord. So the problem of tiles has nothing to do with the landlord of second-hand houses. Unless you find the tiles falling before buying a house, you can refuse the transaction on this ground, but if it falls after buying a house, you can't check out.

Moreover, the brick drop has no substantial impact on the quality of the house, and it is not possible to return a house on the grounds of brick drop. The landlord of the second-hand house did not breach the contract. The second-hand housing contract you signed can't indicate the problem of tiles, let alone have a clause saying that tiles can be returned if they fall off. Since there is no agreement, how can there be a breach of contract?