Legally no, but you can add helper springs, also called overload springs.
Never used these but this is what I am referring to: Ford Ranger Helper Springs, Overload Springs - Hellwig
They shouldn't change the ride of the truck when empty, they only come into play as weight is added to the bed.
The truck was given a legal weight limit that was calculated by Ford when it was made.
It is based on a several things, frame, bed, axle and brakes are a few of those.
If vehicle is involved in an accident or must go thru an inspection/weight station the "legal" limit is what is used, there is nothing you can add to the vehicle that would increase that limit.
Some people find that out the hard way, in the summer where I live the police setup portable scales on the side of the road and then weight trucks with campers, many pass just fine but a few don't, and you have to leave the vehicle there or have it towed, or remove the camper and come back with a vehicle that has the "legal" limit for that campers weight.
So just a "heads up"