No.

Wouldn’t be used for starting an informal communicatoin either, just at the end. Best avoided in any kind of formal situation, even if you hear someone else using it, phrases like ‘well, that wraps it up’ ‘I look forward to meeting with you again’ etc or just ‘many thanks, great meeting’ depending on what is appropriate. You might find this useful - https://englishlive.ef.com/blog/career-english/time-to-finish-five-english-expressions-to-end-a-business-meeting/

NO definitely not in a formal setting. Cheers is informal and predominantly a London term for "thank you" originating from the British pub culture. Only use "cheers informally" to shopkeepers or bus/taxi drivers in London or people you know personally.

I don’t believe it would be correct to use in a formal setting, ‘thank you’ would be more appropriate. Ultimately I believe it does depend on the relationship between the two people as ‘cheers’ can act as an element of covert prestige, where it will be appreciated albeit the formal setting. Contexts where it is more commonly used are for example : • Thanking the bus driver before you get off the bus. • Thanking retail/shop assistants • Amongst friends • Thanking strangers

I have seen that sometimes British people use it at the end of a business email or text message