If it’s somewhere that you already work and you’ve been working hard to develop your skills, then your appraisals, coaching sessions, or reviews would be a great chance to show what you’ve learned (and make sure you bring examples of when they have been actioned) and how it’s impacted your job positively.
If you’re starting a new job and you want to highlight your soft skills, then your CV/resume, cover letter, and your interview are prime opportunities to talk about these skills. And again, providing examples of when you used these skills or when they made your job easier will show an employer you really do have these skills!