The period of verismo opera is 1890 to 1910, contemporary with Debussy and the Strauss tone poems, and the composers are Puccini, Leoncavallo and Mascagni. Operas with roles composed for castrati dropped completely out of the repertoire during the first half of the twentieth century, since they cannot be sung with a verismo technique.
In verismo coloratura completely disappears. In the early twentieth century, before Maria Callas and Joan Sutherland this was the standard for Italian singing. It features a heavy tone and low larynx. When I visit Italy, this seems to be what they are still aiming for. There are exceptions to every rule, of course, but in most of the twentieth century this is what is meant by opera singing. Mario del Monaco may be said to have carried this technique to its most extreme. Here is a sample.
He is at his prime here, and for some this is as good as it gets. Franco Corelli is perhaps his closest imitator, though I don't find Corelli to shout so much.
The technique continues to the present day, but more and more singers choose to take another, lighter path.
This style also reflects the extreme amount of scooping and sliding as well as rubato of any in the repertoire. Del Monaco is not particularly extreme in this department.