Can the Procedure for Design and Development be applied in my company?

First, design and development are not something only applicable to products. It is also applicable to services.

You wrote “sale of electronic products and provides technical assistance services”. I think that the answer to your question

“I would like to know if the procedure for design and development can be applied in my company?”

Depends on how your organization writes the scope of the management system. If the scope is closed, it lists all the technical assistance services provided under the management system, all services are already designed and developed. Any new services provided will not be included under the scope. In that case, design and development are not applicable. However, if your scope is open, if it is more generic, to be applicable to new services to be designed and developed in the future, then design and development are applicable.

For more information about exclusion, the right ISO wording is applicability, consider the following:

• What clauses can be excluded in ISO 9001:2015? - https://advisera.com/9001academy/blog/2015/07/07/what-clauses-can-be-excluded-in-iso-90012015/
• Free webinar on-demand - ISO 9001:2015 clause 4 - Context of the organization, interested parties, and scope - https://advisera.com/9001academy/webinar/iso-90012015-clause-4-context-of-the-organization-interested-parties-and-scope-free-webinar/
• Enroll for a free course - ISO 9001:2015 Foundations Course - https://advisera.com/training/iso-9001-foundations-course/
• Book - Discover ISO 9001:2015 Through Practical Examples - https://advisera.com/books/discover-iso-9001-2015-through-practical-examples/