Page Layout ⇒ Formatting chapter style in REPORT document class

[akshaybelvadi]

I am trying to write my Thesis using LaTeX. I am using the 'report' document class. I have created multiple TeX files (one each for abstract, acknowledgment, and chapters) using 'chapters'. When I use the 'titlesec' package to format the chapter heading it applies to the whole document changing even the table of content, list of figures and list of tables.

I want to keep the default chapter heading style for 'frontmatter' and use a custom chapter style for the 'mainmatter'

Is there a way to apply different chapter style (default/multiple custom styles) to different chapters in the same document? Something similar to 'pagestyle'!