Many deploying service members have various of these instruments, giving a spouse or, if single, a parent or other responsible relative or adult, the power to make certain financial or other decisions if the service member is going to be away for some time. I always had a FPOA good for the cruise length when DH was deployed, in case I had to sell a car registered to him or do other financial business in his name. We always have current health directives. At this stage of our lives, we each have full POAs that activate if the other becomes incapacitated due to illness or injury, and can no longer make decisions, either temporary or permanent.
Naming vengeful or untrustworthy BF/GF, or casual roommates, as holders of a full POA with unlimited powers often does not end well. I would bet every veteran officer or senior enlisted leader who posts here has a few stories about Seaman/Airman/Private Gullible who returns from deployment to find the rent unpaid, car sold, personal goods missing and accounts cleared out. These days, with mobile banking and alerts, it’s easier to get real-time looks at account activity while away from home, as well as set up automatic payments, and deployment alerts with the financial institutions well-known for their service to the military.
This is always a part of pre-deployment briefings. The base legal office or resident JAG can advise and execute these. There is no particular military required format, as I recall. There are versions of these at various internet sources. When I was handling all my mom’s finances, we went to her state’s Department of Aging, downloaded various FPOA and health directives, worked through what she wanted, went to a FedEx store and signed it there for notary purposes.