The answer to your question depends on a lot of things. I’ll start by assuming that your data looks like that in another post you recently commented on (Paraview unable to render World Ocean Atlas NetCDF files), and that your data is in the CF convention and uses structured data.
In this case, to load the data as a rectilinear grid, uncheck the Spherical Coordinates option (preferably before the first Apply). This will load the data as either a rectilinear grid or an image (i.e. a uniform rectilinear grid). However, you cannot directly render a rectilinear grid in ParaView. To force loading the data as a uniform rectilinear grid that can be directly volume rendered, you can also change the Output Type to Image. You may get a warning stating that the OutputType cannot fully represent the data. This is because the netCDF defines the coordinates with uneven spacing, which cannot be represented with data that has uniform spacing.