Hello everyone, I spent days in my search for mangas with the specific criterias mentioned above in the title back when I first started out, so to save some newcomers from having to spend hours themselves, I decided to make this post as a recommendation. To clarify a bit more on the criterias, it has to be a) Actual harem (as in the girls accept the mc having multiple love interests, no desire to monopolize, which is why I prefer the term 'polygamy'), b) Have explicit sex and c) Not as strict as the previous two, but preferred setting being fantasy. When i first started to search, I genuinely thought that there would be many that fit those requirements but I'm surprised that there were fewer than I thought. Anyways, since this is a throwaway, I'm gonna be completely shameless and just list out the ones I found so far:

• Isekai Meikyuu de Harem o (Also has an anime which released recently!)
• Road to Kingdom (Warning: The Novel Has NTR but the manga hasn't reached that point yet, unsure if the manga will actually include that part, so far it has only included a yuri NTR scene, so it should be fine for most for now, but that might change in the future so read at your own discretion.)
• Kami no Techigai de Shindara Zumi de Isekai ni Hourikomare Mashita
• Makenshi no Maken Niyoru Maken no Tame no Harem Life
• Isekai Koushoku Musou Roku ~Isekai Tensei no Chie to Chikara o, Tada Hitasura ✕✕✕✕ Suru Tame ni Tsukau~
• Yuusha ni Zenbu Ubawareta Ore wa Yuusha no Hahaoya to Party wo Kumimashita!
• Astro King - Shoukan Yuusha dakedo Maid Harem wo Tsukurimasu!
• Ataerareta Skill wo Tsukatte Kasei de Isekai Bijotachi to Ichaicha shitai
• Isekai Saikou no Kizoku, Harem wo Fuyasu Hodo Tsuyoku Naru
• Redo Of Healer
• Kujibiki Tokushou Musou Harem-Ken

And That's all I have now, if you guys know of any more that fits this list then please let me know!

Bonus: Doesn't fit the explicit sex criteria but does fit all the others, * Tensei Kizoku no Isekai Boukenroku: Jichou o Shiranai Kamigami no Shito