You can get the latest iPhone 14 models for use with your T-Mobile prepaid plans. The latest iPhones range from $1099 for the Pro Max model down to $799 for the basic model both with 128GB memory. The prices go up for the 256GB, 512GB and 1TB models. Similarly you can get the latest Samsung Galaxy models for similar and higer prices.
At the other end of the scale, you can have several options for more basic smartphone in the $100-$200 range from Samsung, LG, Motorola, ZTE and a number of smaller companies. These are similar to the models available from some other prepaid companies like Tracfone.
Still the phones in the line-up still have fairly large screens, though they're mostly 4GLTE phones.
Plans available for these smartphones start at $40 per month for the regular prepaid plans, but you can also sign up for the cheaper Connect plans.
Here is a list of the basic prepaid smartphones you can from T-Mobile for use with a prepaid plans. Device-only prices are in parentheses. The 5G phones are highlighted.