You can run almost anything in OLAP mode. Usually the tell if something should be run in OLTP vs OLAP mode is if the operation is heavy and not real time.
If using DataStax Studio, you can change from 'Real-time' to 'Analytics' mode using the drop down in the top right corner of each code block (see the attached image).

If you're doing it programatically - you will need to use a instead of g for example gremlin> :remote config alias g database.a
notice database.a
instead of database.g
You can read more about this here: https://docs.datastax.com/en/datastax_enterprise/5.0/datastax_enterprise/graph/graphAnalytics/graphAnalyticsTOC.html