How can I prevent aws console from signing out?

If you are using the console and IAM credentials: For security purposes, a login session will expire 12 hours after you sign in to the AWS Management Console with your AWS or IAM account credentials. To resume your work after the session expires, choose Click login to continue and log in again. The duration of federated sessions varies depending on the federation API (GetFederationToken or AssumeRole) and the administrator’s preference. Please go to our Security Blog to learn more about building a secure delegation solution to grant temporary access to your AWS account.

If you opt to use SAML: then you can restrict it to as low as 15 minutes to as high as 36 hours. Create a URL that Enables Federated Users to Access the AWS Management Console: https://docs.aws.amazon.com/IAM/latest/UserGuide/id_roles_providers_enable-console-custom-url.html

I'd argue that re-authenticating once a day (or every 12-hour here) is not "high level security measures", and should be considered as a baseline. Almost by any standard, the recommendation is not to keep a session alive more that that regardless of activity, for obvious security reasons. (e.g. see 4.2.3 of the NIST digital identity guidelines) So, even if it was possible, I highly recommend not having a session time out greater than 12 hours.