The expanding Earth theory predates the current plate tectonics theory. It is 'abandoned' mainly because of the lack of ideas how the volume (and thus the mass) of the Earth could increase. See Wikipedia, Alternative Physics and Website Dr. James Maxlow.
I'm not a scientist to argue the pros and cons. But I never understood the large Pangaea continent floating around in a huge ocean, and then suddenly break up in pieces and drifting apart. Especially because all our current continents fit together nicely. Not only the one we all can see (Africa and South America), but also all others. Not only closing the Atlantic Ocean, but also the Pacific Ocean.
So I started puzzling with Blender. See below for my first attempt.
Next I will create some high definition maps with details how continents fit together. And by doing that I will probably find some additional data to adjust my Blender globe. So new versions of the globe and new maps will be placed on this web site periodically.
Now some interesting numbers. The current globe circumference (around the equator) is 40,075 km. The diameter is approximately 12,756 kilometers.
Measuring the 'Expanded Earth' globe, I get a circumference of about 25,000 km. That equals to a diameter of 7957 km. That is about 480 million cm less than our current Earth.
The ocean floor is 200-250 million years old. If we use that as our expansion period, the Earth has grown about 2 cm per year. I'm not sure if we're currently able to measure that?
And if you use the period of Earth's existence (4.6 billion years) the growth is 0.1 cm per year...
See also L. S. Myers, A Growing and Expanding Earth is no Longer Questionable.
Well, as I said, I'm not a scientist. So this is not a scientific website. Just something nice to ponder about.
It's always good to be open minded and think about alternative solutions.