hi, you see there are two factors to consider while selecting the size of a light fixture.

First is the total sq. feet area of the room

and

other is the size of table if you want it to be over a table.

keeping it short,

for small dinning room area less than 120 sq. feet prefer pendant lights, for medium and large dinning area use linear chandeliers.

for round table multiple globe pendants will look good.

the other factor table size if very simple to work with. the diameter of fixture should not be more than half of the length of table. If your table is 50 inch wide your fixture should not be more than 25 inches wide.

Hope it helps.