For bold: Hello

Copyfrom telebot import formatting

bot.send_message(
    message.chat.id,
    formatting.hbold('Hello'),
    parse_mode='HTML'
)

italic:Hello

Copyformatting.hitalic('Hello')

underline: H̲e̲l̲l̲o̲:

Copyformatting.hunderline('Hello')

strikethrough: Hello:

Copyformatting.hstrikethrough('Hello')

code: Hello

Copyformatting.hcode('Hello')

If you want parse Markdown, just change parse_mode and replace m with h:

Copy...
formatting.mbold('Hello'),
parse_mode='MarkdownV2'
...

You can see good examples here.