Can I make tomato soup out of tomato sauce?

I just googled it and a bunch of recipes came up, there are probably some that will work to your tastes.

You betcha!

1 Grab a medium sized pot heat it slightly before adding ingredients.
2 Add 2 cans of tomato sauce to the pot, then add a little water, some diced chilis & tomatoes, milk, salt, pepper, and parsley flakes.
3 Bring to a slow boil. Use an immersion blender to puree ingredients. Stir until thickened to the consistency you desire.

Yes. There are lots of tomato soup recipes online, and a few for the copycat Campbell’s tomato soup.