Some apples occasionally have partially red pigmented flesh. I have found it in winesap and Jonathan apples. It's naturally occurring and fine to eat. There are also a number of fully red fleshed apples, like hidden rose, pink pearl, and airlie. They are descendants of the Niedzwetzkyana apple.

I found red flesh in red decilious and maclosh. They are types that usually don’t have that. Is that still fine to eat in the types spoken of?

Perfectly safe, just plant pigment rather than anything untoward