Flush the logs

there a particular size of the daily logs file? lets say the box is going to store logs of up to 200MB and if more is received either it will be dropped or is it like the box will just save the last 200MB received?

if log partition is full, new log cannot be written to log file.

Secondly if the daily logs file size is fixed to certain value can this be increased??

no, log file is not fixed by size. it is rotated according to logrotate configuration.