The phrase "be held by" refers to something or someone that is controlled, owned, or possessed by another entity. Synonyms for this phrase include "be in the possession of," "be under the control of," "be owned by," "be in the custody of," "be in the grip of," and "be subject to." These synonyms can be used interchangeably depending on the context of the sentence and can help to add more variety and depth to your writing. Using synonyms can also help to prevent repetition and make your writing more engaging for the reader.