How do I build an external .NET search engine that utilizes SharePoint Search with advanced/dynamic filtering?

On my website I want to build a .NET Core application which invokes the SharePoint Online search engine (using REST Service) while also meeting specific filtering conditions regarding the managed properties.

I’ve searched for this but only found information on CSOM.

Are there any .NET Core examples on how to utilize SharePoint search and the advanced/dynamic filtering part on this?