Accounting and Crypto transactions

How does accounting work with pure Crypto transactions to other entities?

I am especially thinking of how it is booked in Fiat
(If the total assets change in one year for example)

Can I play some funny games when the rate fluctuates?

Which jursidiction are you asking for? Estonia? Cryptocurrency is treat likes FIAT currency - you need treat Cryptocurrency - f.e BTC XRP as Asset …