Without a license, this is the best sort of antenna for you to use.
https://qrp-labs.com/images/dummyload/dummyload.pdf

To test your radio, a good dummy load is essential.
This is just one way to build one.
Another is to mount it all on the lid of a can so it is shielded when the can is closed.
https://awsh.org/2016/06/22/diy-dummy-load/ has a good instructional.

 

Seems they left one small detail off. Typically, the dummy load can is filled with mineral oil as a heat adsorber. Which also requires a small vent in the can's lid for expansion venting. Can be as simple as thumbtack through the top of the lid with the inserted end bent so that the thumbtack is retained from falling out. That will keep any dust or grime from contaminating the oil and allow expansion without blowing the lid off the can. Also known as a Cantenna.

 

I'm saying that if I had a smaller antenna I would only transmit up to a certain distance? Is that right?

No. Radio waves will propagate unobstructed over an unlimited distance, but get weaker as they do so.

 

Hello,

The propagation of radio waves depand on the frequency and materials they pass.
Have a look at this wiki page:
https://en.wikipedia.org/wiki/Radio_propagation

Bertus