As a clarification, if you write

use Attribute::Handlers;

sub TRACE :ATTR(CODE) {
    ...
}
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Then your sub TRACE will be called once if you write

sub mysub :TRACE { }
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but it will not be called for each call of mysub.

So to achieve what you want, you have to write your TRACE function in a way that, if the appropriate configuration option is set, it wraps the function in a way that makes the tracing happen. Maybe Hook::LexWrap can be helpful for that purpose.