Postgres 12

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CREATE TABLE t (p1 geography(polygon,4326), p2 geography(polygon,4326))

CREATE TABLE

INSERT INTO t VALUES 
(ST_Buffer('SRID=4326;POLYGON((-4.6378495295342015 54.165943975587034,-4.621026714592795 54.165943975587034,-4.621026714592795 54.1566971837205,-4.6378495295342015 54.1566971837205,-4.6378495295342015 54.165943975587034))'::geography,100),
 ST_Buffer('SRID=4326;POLYGON((-4.6405961115654515 54.15348042394744,-4.616563518792014 54.164938989600834,-4.6145035822685765 54.1496601970122,-4.6405961115654515 54.15348042394744))'::geography,100));

INSERT 0 1

SELECT
  ST_Area(ST_Intersection(p1,p2))/ST_Area(p2)*100 AS perc_p2,
  ST_Area(ST_Intersection(p1,p2))/ST_Area(p1)*100 AS perc_p1
FROM t

perc_p2
perc_p1

30.083947379446833
37.906143027573066

SELECT 1