Forced conversion is not possible in Islam.

Quran Bakara Sura ayat 253-257.

And here the will of Ebu Feth Fatih Sultan Mehmet from 1453, which was also law in the Ottoman Empire.

Here is the original in Turkish.

1. Kabul eyledim ki, kendülerin âyinleri ve erkanları ne veçhile cari ola-gelirse, yine ol üslûb üzere âdetlerin ve erkânların yerine getüreler. Ben dahi üzerlerine varub kal’alarını yıkub harâb etmeyem.
2. Buyurdum ki, kendülerinin malları ve rızıkları ve mülkleri ve mahzenleri ve bağları ve değirmenleri ve gemileri ve sandalları ve bil-cumle meta’ları ve avretleri ve oğlancıkları ve kulları ve cariyeleri kendülerinin ellerinde mukarrer ola, müte’arız olmayam ve üşendirmeyem.
3. Anlar dahi rençberlik edeler. Gayrı memleketlerim gibi deryadan ve kurudan sefer edeler, kimesne mâni ve muzahım olmaya, mu’af ve musellem olalar.
4. Ben dahi üzerlerine haraç vaz’ edem, sal be-sal eda edeler gayrılar gibi. Ve ben dahi bunların üzerlerinde nazar-ı şerifim diriğ buyurmayub koruyam gayrı memleketlerim gibi.
5. Ve kiliseleri ellerinde ola, okuyalar ayinlerince. Amma çan ve nakus salmayalar. Ve kiliselerin alub mescid etmeyem. Bunlar dahi yeni kilise yapmayalar.
6. Ve Ceneviz bâzirgânları deryadan ve kurudan rençberlik edib geleler ve gideler. Gümrüklerin âdet üzere vereler. Anlara kimesne te’addi etmeye.
7. Ve buyurdum ki, yeniçeriliğe oğlan almayam ve bir kafiri rızası olmadan Müslüman etmeyeler ve kendüleri aralarında kimi ihtiyar ederlerse maslahatları içün kethuda nasbedeler.
8. Ve buyurdum ki, evlerine doğanci ve kul konmaya ve kal’a-i mezkûre halkı ve bâzirgânları angaryadan mu’af ve musellem olalar.

Böyle bileler…

and here google translated, I don't know many old Turkish words myself.

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1. I have accepted that the rites and rites of their own, in whatever way may be valid, they still fulfill the customs and traditions in style. Even I will not destroy and destroy the swathes of them.
2. I have said that I will not be negligent and inconvenienced by their possessions and their sustenance and their possessions and their cellars and their vineyards and their mills and their ships and their boats and their private commodities and their private parts and their sons and their servants and their concubines.
3. Even the moments can be colorful. Like my other countries, those who can sail from the sea and the dry, can be exempt and musellem from being someone's obstacle and humor.
4. Even I can not impose tribute on them, as if they were unfaithful. And even I can't keep my evil eye on them, just like my other lands.
5. And may their church be in their hands, the reciters by their rites. But they release bells and nakus. And I do not alub masjids of churches. Even these do not build new churches.
6. And the Genoese merchants come and go, plucking from the sea and the dry. Customs issues. To te'admiss someone to moments.
7. And I said that I will not accept a son for the janissary, and those who do not convert an unbeliever to Islam without their consent, and whoever they become old among themselves, will be buried for their benefit.
8. And I said that falconry and slaves may be placed in their homes, and the people of kal'a-i mezkûre and their bazaars may be exempt from drudgery and become a musellem.

They know like this…

Sharia makes no distinctions between religious people. Right is right and wrong is wrong. christians were like muslims. they also paid the same taxes.