What is the best way to organize classes with a large number of fields?

Question

OOP

The question is this. There are entities that can have about 50 properties (this number may change periodically during the life cycle of the software). I see two main options for organizing such classes:
1. In the forehead: a class in which there are a lot of fields.
2. Create your own simple universal structure for storing the "field name" - "value" link (with the necessary methods for writing and searching) and push everything into an array or list, where each element is an instance of such a structure.
You can make both options work, but which way is better? Or are both bad, but is there a pattern that makes sense?
By the way, if the option "on the forehead" is not used for a large number of properties, then where is the boundary usually drawn in practice, are these properties many or few?
I have almost no "combat" development experience, so I ask for advice from experienced comrades.

Answer 1

If the properties are known in advance, then use "on the forehead".
If the properties can change (for example, based on a reference book from the database), then the second option.

Answer 2

Pattern builder (Joshua Bloch) is probably what you need.