Sometimes it helps to conduct a simple Google search and work with what you get.
Doing that, you'd find an existing lib for BPMN integration, ie bpmn-js.
But since that one might be tricky to implement in your Angular project, there also seems to be an Angular version of it, see Angular example for bpmn-js.
I suggest you take it from there, try out a few things and if that doesn't work out, you come back with actual code and a well formulated question.
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