Do you get snow?

tj

No.

Is the area shady? Perhaps they are searching for more sunlight.

There is some shade from the fencing, but they are not covered by the patio cover. Once they pass the height of the paio cover, they have access to full sun from that height onward.

The lax habit is most likely due to inadequate sunlight at the moment.. These maintain their best form if in full sun from the second they are planted. Any shade at all can cause them to lose tightness and become "bushier".

So, now that the tips are growing past the height of the patio cover and can get full sun, should they start growing in tighter forms from this point on?

Will any form of fertilizer help this along?

Start taking no more than a foot off the bottoms of each tree each year, gradually exposing the trunk. Do this every year for the next 5 years. Stop removing growth at fence height. You will see nice trunks develop, and the privacy foliage will begin at fence height where you said you want it. When you encounter a double trunk develop, select the strongest one, remove the weaker one. You may have to stake the remaining trunk for a couple years to straighten it out if it leans from the vertical.

Growth will thicken once the fence and porch roof are cleared. No further training will be needed at that time.

Moses.

The privacy fence and porch roof DO block sunlight from hitting the lower growth, hence the limbs growing lax. Tying them up will help little.

Moses.

Trimming into a tree shape up to the fence line sounds interesting, but risky.

It could tun into a disaster that cannot be undone. I have never seen Blue Arrow junipers trimmed that way,