Commas after Introductory Elements
Some introductory elements don't require a comma, and sometimes the subject of a sentence looks like an introductory element but isn't. Do not use a comma in the following cases:
This lesson introduces how to use commas with introductory elements.

--aftereach introductory element if there is
A comma is used to set off parenthetical elements in a sentence. The parenthetical element (also known as an aside) is part of the sentence that can be removed without changing the essential meaning of the sentence.
Introductory elements require a comma often, but not always!
If the introductory element of the sentence is very short, it is permissible to omit the comma. If the introductory phrase is more than about three words, the comma is recommended.
Commas and Introductory Elements: Phrases | …
Introductory clauses are dependent clauses that provide background information or "set the stage" for the main part of the sentence, the independent clause. For example:
Your student will learn about adding commas to introductory phrases.
When an introductory adverbial element seems to modify the entire sentence and not just the verb or some single element in the rest of the sentence, put a comma after it.
Commas After Introductory Phrases | Grammarly
Note that a comma is not always needed in direct speech if another punctuation mark serves to separate the quoted element from the rest of the sentence. Look at the following example: