How to make a web application developed using angular 9 to GDPR compliant

Please let me know how to make a web application developed on angular 9 a GDPR compliment

can local storage be used? if not what is the alternative.

I understand we need to show the GDPR consent message to the user asking to accept or decline.

Say example the application is developed with local storage, if the user accepts the consent than fine. but if the user decline, how can we handle this.

Is my understanding correct ?