3 words keyword

[DailyLifeImages]

Can I add keyword of 3 words like 'horse in desert'?

[George_F]

Yes, although I'm finding more frequently that Stock sites in general are detecting redundant keywords, so horse and horse in desert may be considered redundant.  So I've been sticking mostly to single words lately.  So I would put horse and desert separately, but that comes down to personal preference.

[Jill_C · Accepted solution]

That's a phrase, not a keyword. Compound words are discouraged unless they are in normal usage. Imagine how a Buyer would search for an image. They wouldn't type "horse in desert" in the search box. They would type "horse,desert".
Read the Adobe Stock Help pages on keywords for a better understand of when compound words might be useful:

Create titles and keywords to help content sell (adobe.com)

[Abambo]

Use that in the title. Keywords should be key-words, not sentences.

[RALPH_L · Accepted solution]

If you did a search by yourself, you would have noticed that  the search for "horse, desert" and "horse in desert" both brought 74,964 results. This leads me to the conclussion that prepositions do not play a big role in searching.