Can we change file without readin it into a memory, if we know that size of file will not change? c++

Question

I know that we can use .seekg() for std::ifstream and read from different places in file with out reading it all in memory. How can we write in different places in file, if we know that size of the file will not change after our actions (we want just change some bytes) without copy it into a memory and saving it as new file?

For example: I have file:

abcdefgh1234567890

I want to set 'de' into a '00':

abc00fgh1234567890

But my file is too large for reading it all into my memory