ABAP consultant involves in writing interfaces, custom function modules, writing ABAP programs in the design of back ground jobs. To name a few, Any custom changes you need while releasing data to SNP from DP,any changes to data while fetching from external sources, some user defined functions that we use in macros...creating custom tables..etc
As you gain the experience as a functional consultant and with a training for short duration you can even become techno-functional consultant. I think it does not require an expertise in objetcs, idocs ..etc.
This blog might you some idea:
or job descriptions like
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