Larger pot will work

The branches and leaves at the top are larger than the base of the pot which creates a high tipping point and the container is as large as I can manage.

A pot with wider bottom will help. Some styles are more prone to tipping over than others. Also the heavier the pot, the better... sort of. Less prone to blowing over but (much) harder to move. Also if you use gritty mix it is so heavy it acts as an anchor, but again- hard to move without a dolly.

I've tried securing pots to stakes in the ground and so forth but none of it really worked, but best results, albeit not perfect, came from the advice above. Good luck!

I've searched for a wide base container with no luck. I have to move it with a dolly now, so not sure if there is an answer. We put it on the concrete patio/apron of the pool so no staking possible.

My best advice was also a wide/squat pot. I have some which are 10+ft tall with 50+ tips which don't tip over on a normal windy day (microburst winds excluded). Find a way to lower the C.O.G. A few very big rocks placed on top of the soil can help. Another option I used for some large plumerias on a rooftop was to build out of wood a frame and brace structure around the container to artificially "widen" its footprint.

Great advice above. Unfortunate that none of it can be utilized....Or just prune it. that may be the best hack you can do.

We've one tall plant that we put in a pot with a weight in the bottom and this seems to help.

What I did is anchored the tree with lope to the ground.