Python or QBasic have an inmediate mode because they are interpreters.
FreeBASIC is a compiler only. The Quick Run found IDEs as FBIde
is the closest you can do with a compiler.
It is not like inmediate mode where variables are kept available for the next command you type. In a compiler Quick run the program runs and terminates, erasing its memory, so everything you want to test or print must be in the code before you launch it.
The code is saved before launched so if you come with something interesting you don't risk to have it lost in the screen buffer...
Doing a FB interpreter mimicking the compiler would require writing another 100000 lines of code, you have to be Microsoft to do that...