New XTEINK X4 Pro User

I’ve just installed it. Found it a bit confusing. Instructions are limited.
The form factor is lovely, small light, sticks to the phone but goes over the edge.
Didn’t realise it can’t read PDF’s. Books I had moved to the memory card weren’t showing up. That was temporarily confusing. I’ll need to convert them to ePub.
It seems to do this automatically in the App when transferring from the cloud.
Charging is not well designed (or USB ). The design of the cable head means it doesn’t sit flat and the cable itself easily twists to remove the connection. I’m sure that could have been designed better.
Font is the real issue. The lack of the option to increase font size dynamically like you would in a kindle. I think you can download bigger fonts but I’m not clear which one is a bigger font. Books are illegible the way the reader is currently.
Is installing Crossink or Crosspoint the best option. Will I get a bigger font (is it easily adjustable)?
People are divided on what is better. I just want something that makes transfer more straightforward, pdf reading if possible and adjustable font. I don’t need any other bells and whistles. Any recommendations?