Why does Reiss transform into a Huge Titan that’s bigger than most other Titans?

The reason behind of Why was Rod Reiss so big in his Titan form? Why haven’t the Marleyans used this to create an army of huge Titans are –

1. It’s probably a combination of things. That serum he ate was specifically for Historia. He licked the serum off of the ground instead of injecting it into his bloodstream. He didn’t take in the serum’s full dose only part of it. He’s a member of the Reiss Royal Family, so something related to their genetics is probably a factor.
2. The Marleyans haven’t figured out how to control him yet and make him do their bidding. In the beginning of season 2, we saw that Rod Reiss was really big in his Titan form.
3. There’s a theory that abnormal titans, such as ursula, are much bigger in size than the average titans because they’re made by combining multiple titans.
4. The reason behind of Why was Rod Reiss so big in his Titan form? Well, he is a member of the Reiss royal family and he licked the serum off of the ground instead of injecting it into his bloodstream.
5. Reiss transforms into a huge titan when he eats the Ymir Fruit, which is very rare. The Ymir Fruit is known to make anyone who eats it feel like they are an ultimate being.

There’s a lot of debate on why Reiss transforms into a Huge Titan that’s bigger than most other Titans. One theory is that he transformed due to his excessive emotions. He was so taken with Eren and Mikasa, who were his fellow recruits, that he transformed because of how happy he was with them.

5. We can also say that Rod Reiss is big in size because he ate a lot of people. (also read: Is Eren Yeager a Titan Shifter?)
6. The abnormal titans created as a result of unnatural  gene manipulation like the Colossal Titan, Rod Reiss, and the Armored Titan are much bigger than the average titans.
7. The serum he ingested was specific for Historia.
8. It’s also possible that the serum contained some of Eren’s DNA which is why Rod Reiss transformed into a Colossal Titan.
9. The serum was made up of the Reiss family’s sperm, Historia’s blood and the Colossal Titan’s spinal fluid.
10. Reiss transforms into a huge titan when he eats the Ymir Fruit, which is very rare. The Ymir Fruit is known to make anyone who eats it feel like they are an ultimate being.

There’s a lot of debate on why Reiss transforms into a Huge Titan that’s bigger than most other Titans. One theory is that he transformed due to his excessive emotions. He was so taken with Eren and Mikasa, who were his fellow recruits, that he transformed because of how happy he was with them.

11. Reiss is the Female Titan who attacked the Survey Corps at Wall Rose. She is one of the most mysterious characters in the Attack on Titan series. Her motives for attacking humans are shrouded in mystery. The Survey Corps doesn’t know her name, or where she came from or why she has taken on such an important role in leading other Titans against them. All they know about her is that she is very strong and can change into a human appearance.
12. He transforms into the huge Titan for one main reason – to show off his power.
13. After Historia tosses the syringe, she flips Rod on his back. This is the only time in the series that we hear an audible crack of bone. It is also the first time we see Rod’s spinal column.