You can download the MCL Mangai font in .ttf (TrueType) or .otf (OpenType) formats from several reputable repositories:
Smartphones do not natively install system fonts without root/jailbreak. Instead, use apps like iFont or FontFix : Mcl Mangai Tamil Font Download Free
The official Tamil Fonts website (maintained by the Tamil Internet community) hosts legacy MCL fonts. You can download the MCL Mangai font in
the font file to open the preview window and click Install . Mcl Mangai Tamil Font Download Free