Thanks for the question. To be clear, DSE does not support "standalone Solr" operation. Rather, DSE deeply integrates Solr with Cassandra. The analog in Cassandra to Solr "multi-core" is simply to multiple DSE/Cassandra column families, and also to use Cassandra's multi-node cluster capabilities. On a single node in DSE/Cassandra, there will be one Solr core per Cassandra "column family". Each Cassandra column family will be "partititioned" (analogous to Solr "sharding") across multiple nodes of the DSE/Cassandra cluster. DSE/Cassandra has "RF" or "Relication Factor" which is analogous to Solr "replicas" - all managed automatically, although DSE/Cassandra keeps replicas of the solr core of one node on some subset of the other nodes of the same cluster, and those replica nodes in turn keep both their own data and replicas of some subset of the documents/rows that are owned by Solr cores of other nodes, rather than having separate nodes for replicas as in SolrCloud.
DSE is somewhat similar to SolrCloud in that documents will be automatically indexed in the proper partition and replicated as needed regardless of what DSE/Solr server/node the original request is sent to.
In short, simply setup a DSE cluster/ring with some number of nodes and some number of column families and you have the equivalent of Solr multicore and SolrCloud.