You don't say what plotting you want, but PROC GLM has many built in plots available.
https://documentation.sas.com/?cdcId=pgmsascdc&cdcVersion=9.4_3.4&docsetId=statug&docsetTarget=statug_glm_syntax01.htm&locale=en#statug.glm.cglmfplots
Also, take a look at using the STORE statement in PROC GLM, followed by plotting using PROC PLM.
https://documentation.sas.com/?cdcId=pgmsascdc&cdcVersion=9.4_3.4&docsetId=statug&docsetTarget=statug_introcom_sect068.htm&locale=en
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