The question isn't whether it makes a difference, the question is whether the model you're working with / the platform you're working with it on already does that. All of the major commercial models have their own system prompts that are quite detailed, and then the interfaces for using the models typically also have their own system prompts (Cursor, Claude Code, Codex, Warp, etc).
It's highly likely that if you're working with one of the commercial models that has been tuned for code tasks, in one of the commercial platforms that is marketed to SWEs, that instructions similar to the effect of "you're an expert/experienced engineer" will already be part of the context window.
It's highly likely that if you're working with one of the commercial models that has been tuned for code tasks, in one of the commercial platforms that is marketed to SWEs, that instructions similar to the effect of "you're an expert/experienced engineer" will already be part of the context window.