Bangla language as dialectic language on my iPhone 17 Pro Max with latest updat

According to this document, Bangla IS supported as the System Language in iOS.

iOS and iPadOS 27 - Feature Availability - Apple

You can change the language used on your phone as described here:

Change the language on your iPhone or iPad - Apple Support

If you mean a particular Bangla dialect/accent --> iOS and iPadOS 27 - Feature Availability - Apple (IN)

This is the important limitation.

If by dialectic you mean something such as Kolkata Bengali, Bangladeshi Bengali, Sylheti, Chittagonian, etc., iOS does not provide separate dialect selections in the normal Bangla keyboard settings. The Apple keyboard is essentially Bangla/Bengali, rather than a menu of regional dialects.

QuickType Keyboard: Multilingual Typing

• Bangla
• Cantonese (Traditional) — Phonetic
• Chinese (Simplified) — Pinyin
• Chinese (Traditional) — Pinyin
• Czech
• Danish
• Dutch (Belgium)
• Dutch (Netherlands)
• English (Australia)
• English (Canada)
• English (India)
• English (Japan)
• English (New Zealand)
• English (Singapore)
• English (South Africa)
• English (United Kingdom)
• English (United States)
• French (Belgium)
• French (Canada)
• French (France)
• French (Switzerland)
• German (Austria)
• German (Germany)
• German (Switzerland)
• Gujarati
• Hindi
• Icelandic
• Indonesian
• Italian
• Japanese (Romaji)
• Korean (2-Set)
• Lithuanian
• Marathi
• Norwegian (Bokmål)
• Norwegian (Nynorsk)
• Polish
• Portuguese (Brazil)
• Portuguese (Portugal)
• Punjabi
• Romanian
• Slovenian
• Spanish (Latin America)
• Spanish (Mexico)
• Spanish (Spain)
• Swedish
• Tamil
• Telugu
• Turkish
• Vietnamese — Telex

If by “dialectic language” you mean speaking Bangla and having the iPhone type it...iOS and iPadOS 27 - Feature Availability - Apple (IN)

Dictation is supported only in...

Dictation

• Arabic (Saudi Arabia)
• Arabic (United Arab Emirates)
• Cantonese (China mainland)
• Cantonese (Hong Kong)
• Catalan (Spain)
• Croatian (Croatia)
• Czech (Czechia)
• Danish (Denmark)
• Dutch (Belgium)
• Dutch (Netherlands)
• English (Australia)
• English (Canada)
• English (India)
• English (Indonesia)
• English (Ireland)
• English (Japan)
• English (Malaysia)
• English (New Zealand)
• English (Philippines)
• English (Saudi Arabia)
• English (Singapore)
• English (South Africa)
• English (United Arab Emirates)
• English (United Kingdom)
• English (United States)
• Finnish (Finland)
• French (Belgium)
• French (Canada)
• French (France)
• French (Switzerland)
• German (Austria)
• German (Germany)
• German (Switzerland)
• Greek (Greece)
• Hebrew (Israel)
• Hindi (India)
• Hungarian (Hungary)
• Indonesian
• Italian (Italy)
• Italian (Switzerland)
• Japanese (Japan)
• Korean (Korea)
• Malay (Malaysia)
• Mandarin Chinese (China mainland)
• Mandarin Chinese (Taiwan)
• Norwegian Bokmål
• Polish (Poland)
• Portuguese (Brazil)
• Portuguese (Portugal)
• Romanian (Romania)
• Russian (Russia)
• Shanghainese
• Slovak (Slovakia)
• Spanish (Chile)
• Spanish (Colombia)
• Spanish (Mexico)
• Spanish (Spain)
• Spanish (United States)
• Swedish (Sweden)
• Thai (Thailand)
• Turkish (Turkey)
• Ukrainian (Ukraine)
• Vietnamese (Vietnam)

Dear engr-nadeem-bd,

It is a change in the language of iPhone. Go to Settings, General, Language and Region and change ur Preferred Language on the top by deleting Bangla and choosing ur language with which u r comfortable.

Regards