Well, your question is very general and vague, so my answer will be, too.
Telegram provides encryption, but needs your phone number. However, some people dislike it for various reasons. It is still assumed to be more secure than WhatsApp, but that seems to be nothing to be proud of.
Also note that you can use a phone number associated with a SIM card that is prepaid and can be acquired
at a supermarket, gas station etc. without your name being registered in any way.
Combining this with some other measures of anonymization and a
short timespan during which you use a specific service via a specific device etc., it is theoretically possible
to achieve a certain amount of anonymization.
As you see, there is a lot of factors that affect the result.