Depends on what you mean by “similar”. If you’re looking for the right thing, there are often a lot of phonetic hints in kanji.

For example, 矢 and 夫 sound completely different, totally unrelated. These are pretty basic kanji though; I think it’s analogous to how O and Q are totally different, or i and j.

If there’s more complex similarities though, then yeah there can be an implied phonetic relationship. Look at: 同胴洞銅恫桐粡. These can all be pronounced the same: どう (dou). Though, many of them have kunyomi readings that are totally unrelated.