The word "dhamma" is defined at length by the Pali English Dictionary. Per that definition, the word "element" can be used in the sense of "a dhamma", as a part of the Dhamma and not in the sense of the "four elements".
The Buddha does discuss the four elements, but although translators avail themselves of the word "element", it actually comes from a different Pali word, "dhatu".
SN14.30:1.4: Pathavīdhātu, āpodhātu, tejodhātu, vāyodhātu—
SN14.30:1.4: The elements of earth, water, fire, and air.
Unfortunately, the translation of two different Pali terms as "element" can lead to some confusion between a "part of the teaching" and the "four elements". To avoid such confusion, it is useful to learn a bit of Pali to understand the full meaning of the suttas.
The Buddha taught the Four Noble Truths: the existence of suffering, the origin of suffering, the end of suffering and the path that leads to the end of suffering. They are all real and true.
As we can see from the dictionary, the word "dhamma" has a tremendous scope and specific meanings according to context. That breadth of meaning actually makes it difficult to make statements about dhamma explaining dhamma. Such statements tend to sound a bit like "does truth explain truth?"
I'm not sure what you mean exactly by "suchness". Perhaps you meant what the teachings refer to as "present knowledge":
SN12.33:11.1: A noble disciple understands choices, their origin, their cessation, and the practice that leads to their cessation. This is their knowledge of the present phenomenon.
SN12.33:11.2: With this present phenomenon that is seen, known, immediate, attained, and fathomed, they infer to the past and future.
SN12.33:12.1: Whatever ascetics and brahmins in the past directly knew choices, their origin, their cessation, and the practice that leads to their cessation, all
of them directly knew these things in exactly the same way that I do now.
SN12.33:13.1: Whatever ascetics and brahmins in the future will directly know choices, their origin, their cessation, and the practice that leads to their cessation, all of them will directly know these things in exactly the same way that I do now.
SN12.33:13.2: This is their inferential knowledge.
SN12.33:14.1: A noble disciple has purified and cleansed these two knowledges—
SN12.33:14.2: knowledge of the present phenomena, and inferential knowledge.
In a sense, the Dhamma may be understood as the teaching that our "windshields are dirty". The dirtiness obscure our vision and results in much suffering. When we clean our windshields, we can see things as they are.
ud1.10:8.2: ‘In the seen will be merely the seen; in the heard will be merely the heard; in the thought will be merely the thought; in the known will be merely the known.’
