i just bought a third generation SE that comes with a USB-C TO LIGHTNING POWER CABLE. CAN I CHARGE THE PHONE WITH tHE OLDER LIGHTINING CABLE AND TRANSFORMER BBLOCK?

Here’s the long answer: You already have probably a dozen or more USB power sources, and cables, all of which can be used to charge your new phone. See this Apple support article→About Apple USB power adapters for information on power sources for charging your Apple device.

Quoting that article:

As part of our efforts to reach our environmental goals, iPhone models no longer include a power adapter in the box. iPhone continues to work with existing power adapters and USB-A to Lightning cables, such as those included in prior models. iPhone models now include in the box a newer USB‑C to Lightning cable that supports fast charging and is compatible with USB‑C power adapters and computer ports that you might already have. You can use either a USB-A to Lightning cable or the newer USB-C to Lightning cable with your iPhone.

Fortunately, in addition to Apple many other technology companies have made the right environment move of not overloading the world with billions of redundant accessories that will eventually end up in landfills or poison the environment or the people who ultimately end up having to disassemble the devices that contain toxic components. Samsung and several other vendors also no longer include power sources with their phones and tablets.

I'm not sure that was the question. Putting aside the terminology used, I think the question is about whether or not it's OK to use a USB-A to Lightning cable plus a USB-A power adapter with a new iPhone SE 3rd gen.

There are caveats though. If it's an older 5W power adapter, that will be really slow. I prefer to use a power adapter that's at least 10W.

Yes. That's probably the most common way and works just fine. It might be a little bit slower, but it's safe and shouldn't affect the reliability of the device nor the battery.