Can I send HTTP GET request with body from browser?

TLDR; No.

Despite the fact that HTTP/1.1 spec seems to not restrict GET requests with body any longer accordingly to this thread, this seems to be still not supported by browsers nowadays. Doesn't matter whether you use XMLHttpRequest or fetch api. The following browsers were tested: Chrome 74, Firefox 66, Safari 12. Below are examples with output for fetch api:

Chrome 74

TypeError: Failed to execute 'fetch' on 'Window': Request with GET/HEAD method cannot have body

Firefox 66

TypeError: HEAD or GET Request cannot have a body

Safari 12

TypeError: Request has method 'GET' and cannot have a body

Just consider this when designing your public api endpoints.