I don't understand the question.

Panels have ratings.
They also have maximum branch circuit ratings. Typically this is 100 or 125A.

Just to piggyback on Stan's response.

The manufacturer of the panelboard will also release the technical specifications for the board. Within those specs will be a description the breakers that can be used in the panel board.

For example, Square D manufactures an 82 position panel. The Main Breaker size is 225 Amps. The largest size breaker that can be used in the panel is a 200 Amp breaker.

Obviously if you can install a 200 amp breaker you can install a 150 amp and a 50 amp. In fact go look at the panel you have now. You will see at least one 30 amp (electric clothes dryer breaker) and a 40 amp Heat breaker.

The issue is not the size of the breakers it is the calculated size of the load to be served by the panel.

Getting the calculated load for a residence, is difficult and in my opinion should only be done by a licensed electrician.

Brian, did you maybe want to clarify a little bit as to what it is you want to know?

Meter and 200 amp breaker, one unit (no extra breaker or space). Would like to feed another 200 amp utility panel and from that feed to sub panels (150 and a 50) Load cal;s are good.

...

OK, re-reading it I get what you are saying.

It is rare to find a 200A panel, main breaker or main lug, that will accept a 150A branch circuit breaker. Most likely the largest you will be able to run is a 125A sub-feed.

Geeze!

Let's try it this way, please, what is the model number and manufacturers name for the panel you have installed.

Do you have a 200 Amp Main Breaker panel or a Main Lug Panel?

You said that all of the slots are full on your panel, how many slots does your panel have?

What in heaven's name do you mean by, "... the calcs are good."?

How about telling us how many amps the calculation says are needed.

Do Not Add the the amperage on the circuit breakers. That is not how a load calculation is done.