Q.Foxtail Palms falling over
I have several foxtail palms on my property in Brisbane. The two latest palms I planted are now 4 metres tall; however, both of them have fallen over, as the trunk has shrunk back from the soil exposing the roots. The roots are not strong enough to hold them upright. I have supported the trunks for a couple of years now and the palms have continued to grow; however, the trunks are still not contacting the ground. Is there anything I can do to get them to support themselves or should I remove them?
regards,
Dave

It would seem that your Palms did not adequately grow it's root system to support itself.
This could be due to improper planting, over fertilizing or environmental issues.
At the size that your Palms are they are vulnerable to wind.
There is little to be done at this point except give them the optimum care.
Here is a link to refresh you on their care requirements.
https://www.gardeningknowhow.com/ornamental/trees/foxtail-palm/foxtail-palm-tree.htm