The FHA 203(k) rehab loan can be used to purchase and fix up a home, or you can refinance with it, adding the costs of your renovations. The advantage of the 203(k) loan is that the maximum loan amount is based on the improved value of the home, not its current value. It's kind of like a home equity loan without the home equity. Keep in mind that all FHA home loans require mortgage insurance (upfront premiums plus monthly charges), and those never go away no matter how much home equity you acquire. Here's an article about FHA 203(k) loans that provides all the details -- what improvements qualify, how to determine your loan amount, and what it costs. https://themortgagereports.com/14946/fha-203k-loan-mortgage-lender-rates
Understand that this is not your only home renovation option, and might not be the best. Fannie Mae's Homestyle mortgage also bases the loan amount on the improved property value, and can be used for investment and vacation homes, unlike FHA. It's also almost always less expensive.
Finally, if you like your current home loan, and have some equity, a home equity loan or line of credit might be a much less expensive way to fund home improvements. Thank you for writing, and good luck with your projects.