The only commentaries that I recommend is the chapter summaries of the original AV1611. They can also be found in the 1833 oxford reprint.

They look something like this:

1 The genealogie of Christ from Abraham to Ioseph. 18 Hee was conceiued by the holy Ghost, and borne of the Virgin Mary when she was espoused to Ioseph. 19 The Angel satisfieth the misdeeming thoughts of Ioseph, and interpreteth the names of Christ.


They can also be found online at this site : 

https://www.kingjamesbibleonline.org/Matthew-Chapter-1_Original-1611-KJV/

The authorized version also called the king james bible has its own built in dictionary. 

In fact the kjv is the english language. 

Words are often defined in the same verse. Look especially at the first occurrence of the word. Or in the same chapter. 

Therefore word studies and phrase studies can be helpful to understand the kjv phrases and words.

You can do word studies using swordsearcher for windows

https://www.swordsearcher.com/:

or using Tecarta bible for IOS

https://apps.apple.com/us/app/tecarta-bible/id325955298

unbound bible for MAC 

https://apps.apple.com/jm/app/unbound-bible/id1412836395?mt=12

or if you want to not use a computer you can use strongs dictionary to find all occurrences of a word. Then you dont look at the greek and hebrew you only look at all the verses that contain the word.

https://en.wikipedia.org/wiki/Strong%27s_Concordance

Or you can use Cruden's complete concordance to the old and new testaments instead of strongs. It can be used to find all occurrences of a phrase in the kjv

https://en.wikipedia.org/wiki/Cruden%27s_Concordance

Just reading the kjv is fine too. Especially if reading it from the beginning since words are generally defined the first time they are used in the kjv.

James 3:1 (KJV) My brethren, be not many masters, knowing that we shall receive the greater condemnation.