GoMySQL is a Go module that includes various helpers for MySQL, including mysqlvars, is a simple CLI app to dump the contents of SHOW VARIABLES for MySQL. It writes to STDOUT which can be piped to a file.
% go install github.com/grokify/gomysql/cmd/mysqlvars@latest
% mysqlvars -h <host> -P <port> -u <username> -p <password>
% git clone https://github.com/grokify/gomysql
% cd gomysql/cmd/mysqlvars
% go run main.go -h <host> -P <port> -u <username> -p <password>