Should I add indexes?

Question

MySQL

For example, there is a table according to some entity, for example, with apartments:
- id
- floor (floor)
- area_size (area)
- room_count (number of rooms)
- created_at

By default, when entering my site, sorting is done by creation date ( created_at field), but you can choose to sort by all other values.
There is also a filter to search for all values ​​(including combined ones).

As I know, the index must be added to the fields that participate in where, join, order by, group by.
Do I really need to add an index to all these fields?
Or add only on created_at?
Or not add at all?

Answer 1

add as many indexes as needed to optimize all queries