What is the ruling on purchasing a car through a bank, if the contract is a lease ending with ownership, and the bank buys the car at the customer's request, and the bank bears the car's insurance and chooses the insurance company, and there is no condition for increasing the amount in case of delayed payment, and is it a condition that the bank be Islamic?

A lease-to-own contract can be valid or invalid. A valid one is characterized by two separate contracts (a lease then a sale), and the guarantor in this case is the lessor. The bank's purchase of the car to sell or lease it to you does not affect the legitimacy of the transaction, as long as it adheres to Sharia guidelines. The insurance for the leased asset is the responsibility of the owner. If the bank chooses a prohibited commercial insurance, the sin is on them, and it does not preclude dealing with them. It is not permissible to deal with usurious banks when Sharia-compliant alternatives, such as Islamic banks, are available.