Is GPT-4.5 still available?

Guys, is there any model that is left from the 4 series?

I saw that apparently on the "Get Plus" it saids that you get access to research preview of GPT-4.5. I've never tried GPT4.5, for those of you guys who did, is it similar to GPT-4o in any sense? Or is it a completely different model compared to 4o?

Is it just available on the Pro plan, or also the plus plan?