No, your partner isn't "just gonna figure it out."
NSFW
It's not "unsexy" to communicate with your partner about what you want. If you expect them to know your body from the get-go, you're setting both them and yourself up for disappointment. This is because not everyone has the same preferences as you. Different people have different ways they like to be played during sex, and if there's anything specific that you want done, it's your responsibility to tell your partner about it. If your other finds it to "ruin the mood" to either listen to you when you communicate your desires or to communicate their own, they're not mature enough to be having sex in the first place.
Plus, some people are just shy, overly reserved, or unimaginative. OP has it right: COMMUNICATE!
If you don't, you seriously limit how good the sex can be.
"If he compares hand sizes with you, he wants to fuck you stupid style."
- some vtuber
Yes, we've all seen Tarzan, we know how that works.