Çok fazla var ama kullandıklarımi ileteyim:

BS 4 için:
https://github.com/StartBootstrap/st...rap-sb-admin-2
https://github.com/stisla/stisla
https://github.com/coreui/coreui-fre...admin-template
https://github.com/ColorlibHQ/AdminLTE
https://github.com/BootstrapDash/Maj...Admin-Template

BS 5 için:
https://github.com/adminkit/adminkit