Does this sentence make sense?

This don't read like a normal sentence to me, but some liberties can be taken for lyrics. I agree with others that "a muse" is better than "to muse", but that does change the meaning. The verb muse would be used to describe the person you're talking about being contemplative or thinking deeply. The noun muse would be used for the speaker of this sentence to say that the person you're talking to can use the speaker as an object of artistic inspiration (there are also some romantic connotations). I'm also confused how moonlight relates to musing? It feels like this might come from your native language. Muses (noun) are generally concrete objects or people. Musing (verb) is generally an introspective process--perhaps it could be done under the moonlight?

No, it does not make sense.

Missing a couple of parts of speech, there, to be a correct sentence a few things: "to muse" means to ponder or think about. but "A Muse" is a reference to ancient mythology, and means "to be the thing which inspires" "if you need to muse" = if you need to think about it "If you need a muse" = if you need something to inspire you

it works in a poetic kinda way i’d say

I think it would make more sense to say “I can be the moonlight” or “I’ll be the moonlight” or something similar, as it’s an “If” statement

Yes it makes sense in an artistic manner. I interpret this as, if you need to give inspiration I will illuminate you through the night.

I don't think it makes sense. The way it reads is: If you need to think about something I brought you a flashlight. I am the flashlight. Like... what?? It doesn't make sense. You don't need light to think. Why are you doing this. Please turn off the light it is making me squint and it's giving me a headache. I don't need any sort of light to contemplate things I'm with the other people that say "a muse" is better because there are already cultural connections to muses being goddesses (and there are goddesses of the moon) and the general idea that the moon and moonlight might have mystical or inspiring powers. Poetically, there is a connection that can be made. But unfortunately, despite the similarity of the expressions and the same etymology, "to muse" has absolutely mundane connotations about thought process and "a muse" has connotations of mysticism and romance. Don't do it. Find something more clever or poetic that doesn't force the fit. Lyrically it SOUNDS good, but you have to bridge the gap. For instance you might say "If you want to muse in the moonlight, I can be the moon and the stars in your night sky" or some other rhyme that I can't think of right now but that flows like that and gets from A to B.

As a song lyric, it works, but I think “a muse” (the noun) works better than “to muse” (the verb), because it creates a clearer connection. My $.02.

Kind of. It takes a second to figure out but I like it.