That is correct. Typically you will want your field to be either indexed or stored or both. If you set both to false, that field will not be available in your Solr docs (either for searching or for displaying). See Alexandre’s answer for the special cases when you will want to set both to false.
As stated here : indexed=true makes a field searchable (and sortable and facetable). For eg, if you have a field named test1 with indexed=true, then you can search it like q=test1:foo, where foo is the value you are searching for. If indexed=false for field test1 then that query will return no results, even if you have a document in Solr with test1‘s value being foo.
stored=true means you can retrieve the field when you search. If you want to explicitly retrieve the value of a field in your query, you will use the fl param in your query like fl=test1 (Default is fl=* meaning retrieve all stored fields). Only if stored=true for test1, the value will be returned. Else it will not be returned.