This script allows to convert a WKT geometry to a BBOX string with WIDTH and HEIGHT to be used in a WMS request.

wkt_bbox.sql

-- WKT TO BBOX
-- This script allows to convert a WKT geometry to a BBOX string with WIDTH and HEIGHT to be used in a WMS request.
WITH input_geom AS (
    SELECT ST_SetSRID('POLYGON((7.210196256637572 46.079631239023286,7.2218477725982675 46.07266495408345,7.22425103187561 46.07465966398232,7.212899923324584 46.08162569712192,7.210196256637572 46.079631239023286))'::geometry, 4326) AS geom
)
SELECT 
    'BBOX='||
    ST_XMin(ST_Transform(geom, 2056)) ||','||
    ST_YMin(ST_Transform(geom, 2056)) ||','||
    ST_XMax(ST_Transform(geom, 2056)) ||','||
    ST_YMax(ST_Transform(geom, 2056)) ||'&WIDTH='||
    ROUND(ST_XMax(ST_Transform(geom, 2056))-ST_XMin(ST_Transform(geom, 2056)))||'&HEIGHT='||
    ROUND(ST_YMax(ST_Transform(geom, 2056))-ST_YMin(ST_Transform(geom, 2056))) AS BBOX_W_H
FROM input_geom;