Good weapon against the French?

yes

The King's Indian Attack (KIA) is a viable weapon against the French Defense...

https://www.simplifychess.com/kings-indian-attack/index.html

here Bobby Fischer defeats his opponent in the French Defense in the 1967 Sousse Interzonal using his favorite KIA...

GM Neil McDonald is an expert on the French Defense.....

This excellent book comprehensively and clearly explains how to play the King's Indian Attack against the French (as well as other of Black's tries such as the Sicilian, the Caro-Kann, etc.)...

The King's Indian Attack - Move by Move by Neil McDonald

https://www.amazon.com/Kings-Indian-Attack-Move/dp/1857449886/ref=sr_1_1?dchild=1&keywords=king%27s+indian+attack&qid=1622006025&s=books&sr=1-1

another excellent book on the KIA, which also thoroughly covers it against the French is...

Starting Out: King's Indian Attack by John Emms...

https://www.amazon.com/Starting-Out-Indian-Attack-Everyman/dp/1857443942/ref=sr_1_2?dchild=1&keywords=king%27s+indian+attack&qid=1622006867&s=books&sr=1-2

tarrasch

I usually play the 8.g3 line rather than 8.Be2.  More room to maneuver and attack e6.

Ah so g3 Bh3 and the e6 pawn is soft and f6 may not be possible got it

 Well, g3, h4, and Bh3

join my class and do what ever 805-073-6406

Black does not decide the Milner-Barry Gambit.  It is White that plays Bd3 ousted of moves like Be2, a3, etc.

Diemer-Duhm is utter crap.  Black knows what he is doing, you will lose!

Tarrasch and Exchange are dead equal at best.

3.Nc3 is the absolute strongest followed by 3.e5 and 2.d3 as second and third.