To get genome sizes from UCSC I just use the following code:

import MySQLdb

def ucsc(genome, query):

    host = "genome-mysql.cse.ucsc.edu"
    user = "genome"
    db = genome

    conn = MySQLdb.Connection(host=host, user=user, db=db)

    df = pd.read_sql(query, conn)

    conn.close()

    return df


def chromosome_lengths(genome):

    query = 'select chrom,size from chromInfo'

    df = ucsc(genome, query)

    return pd.Series(df.size, index=df.chrom).to_dict()

But how do I get genome sizes from ensembl through mysql? For example for GRCz11 and GRCm38.p6.

Just giving me the mysql command line command is enough :)