Can I open a project using an older verion in a newer version?

Specifically, a project made in version 2019.1.2 with 2019.1.8

Yes, you can. Be aware tho that things change between versions so your project may require some maintenance right after switching versions. For example some things may become obsolete and your code won’t compile.

Things such as that tend to not change for minor updates so you will probably be fine.