I'm looking for some mangas where the main character gets transported to another world and uses their knowledge to help that world.

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Reality is a momentary dream but a dream is a reality for an eternity.

maybe I can recommend you some series

Jui-san no Oshigoto in Isekai
https://www.mangaupdates.com/series.html?id=141307
(it's new, but exactly matchs with your description (in a not epic way )

Tondemo Skill de Isekai Hourou Meshi
https://www.mangaupdates.com/series.html?id=140468
(it's new too, and I'm not sure if the main char really help the world with his... unique skills - maybe later ^^)

Tate no Yuusha no Nariagari
https://www.mangaupdates.com/series.html?id=107199
(great manga, less about using this knowledge, but the main char is aware about his former identity and the "real world")

Tensei Shitara Slime Datta Ken
https://www.mangaupdates.com/series.html?id=119910
(unusual main char, but I love this manga like Tate, less about using this knowledge, but the main char is aware about his former identity and the "real world")

Arifureta Shokugyou de Sekai Saikyou
https://www.mangaupdates.com/series.html?id=128108
(unexpected mature in the following chapters... I'm not sure if he or the other chars will use their "real life" knowledge)

Kenja no Mago
https://www.mangaupdates.com/series.html?id=133460
(mhm, the main char use his knowledge for sure, but... in some way, it feels strange :/ (but it's funny after all ^^) )

Gate - Jietai Kare no Chi nite, Kaku Tatakeri
https://www.mangaupdates.com/series.html?id=72210
(it's not exactly that the main char is transported in another world and use his knowledge, it's more a clash between the "real world" and a fantasy world)

Maoyuu Maou Yuusha
https://www.mangaupdates.com/series.html?id=64917
(just fantasy, no teleporting chars, but the main chars try to use modern technique (unusual in classic fantasy settings) to build a better world)

Kumo Desu ga, Nani ka?
https://www.mangaupdates.com/series.html?id=129680
(well... the main char awakes in a fantasy world, but she is a spider, so... it's more about surviving, not really helping the world, but maybe interesting after all)

Tsuki ga Michibiku Isekai Douchuu / Moon-led Journey Across Another World
https://www.mangaupdates.com/series.html?id=123153
(I dropped it, don't know exactly if the main char use his knowledges...)

Specifically another world? or do you also want ones that go back in time?

Shoujo/josei:

7 seeds -Teams of people placed in time capsules and wake up wayyy in the future after an asteroid wipes out all life as they know it. The teams were picked for their specific real world skills, and they use them in the future to try and build a life for the teams and kickstart humanity again.

+a no Tachiichi-Otaku-ish girl accidentally gets summoned along with the perky go-getting 'protagonist' in a 'please save our world from demons using x power' type scenario, only she gets the power and is too awkward to say anything so she has to pretend from then on. It very very funny. Anyways, she uses her imagination and fantasy story knowledge.

The Queen's knight-Uses her knowledge to build schools and stuff.

Houshin Shinai Engi-Houshin Engi fan is transported into the book.

Gin no saji and Operation liberate men are girls transported to worlds with a dominating female hierachy and more use their attitudes to help the guys of that world.

Shounen/Sienen:

Drifters-Historical figures transported to a fantasy world at the moment of their death, where they influence the world and attempt to fight back against an evil army that's trying to overtake it.

Ore to kawazu-san no isekai hourouki-Average guy gets transported to a magical world where he uses his magic to create everyday human things for fantasy creatures.

Isekai Houtei: Rebuttal Barrister-Lawyer that implement law in a fantasy world.

Isekai de "Kuro no Iyashi Te" tte Yobarete Imasu-Gamer gets summoned to a game world and is the only one that can use healing magic.

Senyuu-Fits in a very round about way but I can't tell you how, because spoilers. It's a gag manga that develops a surprisingly complicated plot later.

Lasboss x Hero-manga artist gets transported into his manga and can influence it from within.

Outbreak Company - Moeru Shinryakusha-uses knowledge of anime/manga/moe.

Survival/horror:

:Reversal-A geisha that slips into a parallel world during a game and uses her knowledge and heroic attitude to help that world.

Suicide island -suicidal people are dumped on an island where they are allowed to live or kill themselves, their choice. The protagonist decides to live and him and others rediscover various life skills.

Cage of Eden-A plane crash lands on an island full of extinct animals, protagoists are highschool kids that were on a trip and most of them have various club activities that come up.