Ummm...not so much. Southern Baptists are in decline. (https://religionnews.com/2021/05/21/southern-baptist-decline-continues-denomination-has-lost-more-than-2-million-members-since-2006/)

Broadly, evangelicals are about even but church-going evangelicals are being replaced by non-church-going "political" evangelicals.

https://religioninpublic.blog/2020/12/10/so-why-is-evangelicalism-not-declining-because-non-attenders-are-taking-on-the-label/

All the GOP's bases are slowly losing membership while Democratic bases are growing. That's why they are resorting to rigging elections.