Yeah, I'm thinking you need products in addition to a better brush. I've got curly hair, my DD has straight/wavy (not well behaved) hair and my DSs have curly/wavy hair. I suggest the Wet Brush (or one like it) below. It works for all hair types - all my kids like it, too.

As for products, if your hair is frizzy, you likely have more curl than what you think. When your hair is frizzy, it's usually seeking moisture. You could start with a light curl cream. If you like the way it dries but, later in the day, start to experience some frizziness, you can add a light gel on top of the cream. I've learned a LOT about product from social media and then trying different products to see what works best for my hair and my kids' hair. Good luck!

FWIW - I'm 58 and my gray hair is a bit thicker/coarser than my non-gray. It's changed what products I use.

Wet Brush
https://www.amazon.com/Wet-Brush-Speed-Hair-Aqua/dp/B0B75KFXHP/ref=sr_1_5?dib=eyJ2IjoiMSJ9.Fj_VAgpTOlm8XUlBV6I_uK31cMWs73NZaCQq9UFVG9LWa3jca2Kx1m-ix690DqqHFilRJcIaNThXaW5lqFr2bhBHywy5yy9F_xXfTPhbEZ2MmT71U91XBPPhvMFqZ6xVwTRyozI0N3TFH93li1hT2FneOdP-F-MM1MNqwqU5XzFhUFn8FzVUNK3KEHaqfcpOTMAX3rlRdir4OyiMXJaCOEDbVKWw2dotQTVjNJIIIksAfA2Hi9vIu3Sz0DZjSyIRReCQSNSd8PoZioc2LcEwWkm5cu5WpUw7erd32lyy46g.iJW36mr0Uj1UOPF2lSktWLgRlNGUs2ULZ72SM4B3n9w&dib_tag=se&hvadid=616863655875&hvdev=c&hvlocphy=9008189&hvnetw=g&hvqmt=e&hvrand=15741180384312769487&hvtargid=kwd-10825912870&hydadcr=26614_11715055&keywords=wet+brush&qid=1715109219&sr=8-5

My favorite light curl cream. It's not the cheapest or the most expensive. You may want to try one of the ones listed by Byrdie.
https://www.ulta.com/p/curl-light-defining-styling-cream-pimprod2028145?sku=2587675

Byrdie recommended light curl creams
https://www.byrdie.com/best-curl-creams-4587047?utm_source=googlepaid&utm_medium=con&utm_content=CjwKCAjwouexBhAuEiwAtW_Zx2gEwbZAMsKLP-o5wW5Se5MaEeOeQersSWry9aC1jgstvMvTXssHCxoCjkQQAvD_BwE&utm_campaign=commerce-dd-CurlCreams_Byrdie_Combined_CommSEM_OrganicLP-4587047&utm_term=best%20curl%20cream%20for%20wavy%20hair&gad_source=1&gclid=CjwKCAjwouexBhAuEiwAtW_Zx2gEwbZAMsKLP-o5wW5Se5MaEeOeQersSWry9aC1jgstvMvTXssHCxoCjkQQAvD_BwE

Shoulder length or just below. It definitely has waves but feels frizzier/wiry-ier by the day. Usually in a ponytail or messy bun but would like to wear it down more. Generally have not used products as I was lucky to have straight/wavy, well-behaved hair. No more so I need to embark on some type of regimen.

Is your hair long or short? Is it straight, wavy, curly? What do you 'embrace' about your hair? How do you usually wear it?

Looking for suggestions for the best round brush for gray, but died, mid 50's hair. I think my current brush which needs to be replaced is contributing to my hair breaking and increasing frizz/wireness when drying. But, there are so many choices in so many price ranges. Recommendations welcome.