Subtitle size on synced contect and cloud sync

I’m experiencing some strange behavior regarding subtitle size. As a PlexPass user I’m enjoying both cloud sync and offline sync to my Android devices for my TV Shows.
Depending on the show, the subtitle size is changing considerably. For some videos it is huge and for other I can barely read it.
Is this related with subtitle format (all of them are srt files)? Is there any way of setting subtitle size for synced (transcoded) content?

Many thanks in advance.