Is it possible to transmit radio signal with cheap 433Mhz transmitter as strings and receive it with an RTL-SDR
In general you can use RTL-SDR to decode any AM and FM modulated signals (+some digital modulations) that lie within the frequency range form roughly 50MHz to about 1GHz. So 433MHz is confortably within that range.

There are many projects on GitHub that leverage the RTL-SDRs ability to decote 433MHz OOK modulated signals like:

RTL_433
Which comes with a ton of decoders for various appliances.

OOK_Decoder
Which will give you the demodulated raw output for you to decode the bits yourself.

I'm sure you will find more but those are in my opinion the most noteworthy for the 433MHz OOK space.