An air filter with a higher MERV rating will cause greater resistance to airflow, typically resulting in a reduction of airflow. This can have an unwanted effect on the cooling side of an HVAC system, as the cold coil can eventually freeze and become an ice ball, restricting airflow completely. Studies have shown that filters with higher MERV ratings capture higher percentages of particulate matter as well as smaller particles. A MERV rating is a good indicator of the effectiveness of an air filter in your central HVAC split system, with higher ratings providing better filtration.
To achieve a MERV-13 rating, a filter must trap 90% of the particulates in the 3-10 µm range, 85% of the particulates in the 1-3 µm range (where PM2.5 is), and 50% of the particulates in the 0.3-1 µm range (the really very small). Reducing airflow in your system can worsen air quality in your home and put a detrimental amount of pressure on the fan in your boiler or air conditioning system. Air filters of different sizes and MERV ratings will have different prices. Technology for HVAC units has progressed since then, and most modern units should be capable of at least one MERV 8 filter.
Owning pets would require a MERV 10 to control their dander, which tends to have smaller particles than other contaminants. It would seem that increasing the size of the filter will only help slightly, and physically it could be difficult to adapt in a generalized way.