First hit when you Google it:
Installation of Resistors on 4 ohm Dash Speakers This Modification Applies To Non-Alpine Dash Speakers The Setup I have a 2018 Ram 1500 with the stock 6 speaker stereo system and 8.4 Uconnect. I replaced the stock dash speakers with Polk DB351’s. These are 4 ohm speakers; the stock 3.5”...
www.ramforum.com
Car speakers are typically 4 ohms. Ram messes that up electrically by wiring the dash speakers and front door speakers in parallel, which would typically create a 2-ohm load. Ram attempts to compensate for this by installing 8-ohm speakers in the dash. Also the dash speakers need less power, so it kind of works okay that way.
Also I would read up plenty if you are expecting more bass out of aftermarket door speakers with the low power that you are getting from the factory head unit.
Curious, why not 6x9's for the doors?
Another thing to consider, is sound treatment for the doors. I just finished my 2021. To do it right you have to take the entire door apart, including disconnecting the window, but worth it in my opinion. Dollar for dollar, some say door treatment makes a bigger improvement than the speaker upgrade. Ambient noise from doors, engine, tires, wind, etc. wreaks havoc on the sound. Brand of speaker you run off your factory headunit may not matter much.
The dash speakers were the first component I replaced to tone them down, but one thing I never tried was disconnecting them to see how that sounds. Depending on your preference for bass, you may get all the midrange and treble you need out of the four door coaxials alone. I think the dash is not the greatest spot for a speaker to begin with and doubling down on the headunit front channels doesn't make much sense to me electrically either.