「風」 in 「風景」 and 「風光」 carries the meaning of :
'Style': as in 「和風」 (Japanese style) and 「作風」(style of behavior)
'air; atmosphere' - (something that creates moods and evokes feelings)
「景」 in 「風景」 carries the meaning of 'scene/ sight' -- the picture you see in your eyes, as in 「奇景」(strange sight)，「場景」(scene in a play)
The term 「風景」 (sight/ scenery) specifically refers to 'the sight of a landscape or a natural scenery' as in 「看風景」(watching the natural scenery )
「光」in 「風光」refers to 'light', which is needed to enable people to see -- in another word: 'sight'.
The term「風光」 generally refers to 'sight/ scene /scenery'
For example:「異國風光」(sights and scenes of foreign country) ;「園林風光」(sights and scenes of garden and forest)
Of course it includes 'landscape or a natural setting' For example:
「西湖風光」. Therefore 「風光」and「風景」are interchangeable in this sense. (You can write 「西湖風景」instead of 「西湖風光」)
Unlike 「風景」, 「風光」can also be used metaphorically.
「風光大葬」(scenic funeral = impressive, dignified funeral)
「風光了幾十年」( have been a sight to behold for decades = have been awesome for decades)