How is the size of oceans fixed? I found that pacific ocean is increasing in size. How?

i think the ocean increasing in size because of the land is ruin up..when theres more bulding or skyscrapper built,the land becomes heavy day by day and this is lead to the sink of the land...actually,the ocean doesn't increasing in size,but the land is sinking nowadays..

Coastal erosion is reducing the surface area of many low lying islands ,combined with increasing water levels due to polar ice melt.Possibly Asia and America are moving apart on a geological level but this could only be at a rate of mm per year.

May be because of Ocean spreading and continental plates coalescing further. But, this is on geological scale and slow.
Pacific Ocean is larger than the combined land area by a sixth and is half of total Ocean & Sea areas. Ocean area in a grid format is computed by measuring the area squares. Now computers do that work.

Decreasing, as the North American continental plate moves westward and the Pacific plate subducts beneath. Meanwhile, the Atlantic ocean is getting wider as the North American plate is moving away from the Eurasian plate as ocean crust is being formed along the mid-continent rift. (spreading sea-floor)

There is always the thought that:
With the glaciers and northern ices melting, water level would be rising causing the ocean to cover more shoreline resulting in the ocean being a bit larger.