https://birgittaville.com/2023/02/24/harmonizing-scales-on-guitar/
Follow this page for written instructions.

Harmonizing the C Major Scale

• 3rds, 6ths, 10ths, 13ths, played horizontally on each string set. YouTube Playlist.

After practicing these on the fretboard, practice them mentally away from the guitar.

• 7th chord arpeggios to the ii V I progression, played in each position; two octaves.
• Triad inversions, to the IV vii I progression, played in three positions on each string set.
  • Play the triad up each string set, for each chord, one position at a time.
• Stacked 4ths, played up the neck horizontally, on top four strings. E.g., fbea, gcfb, adgc
• 7th chords, played horizontally the up neck: 3x1x7x. x3x1x7. 1xx3x7. 3x157x. x3x157
• Triads, up each third. Move only one note.
  • From positions XIV to V, on each string set. E.g., C/Em/G/Bmb5
• 7th chords. C or B, E or F, as lowest note. On strings 6543, 5432. 5321. 4321
• 9th chords: I (st 5-2) / IV (st 4-1) / V (st 6-3).
  • M: 13M79. 1379-#9-b9. 1369. 1359. m: 1b3M79. 1b379-#9-b9. 1b3#59. 1b359.

Harmonizing Altered ScalesLearn the less common chords by seeing their relation to familiar chords:

• C/CM7/C7/Cm7/Cdim/Cm7b5/CmM7/CM7#5 In pos. III, III (no 4th st.), VIII. X.

Play the following harmonized 7th chords in pos. III, III (no 4th st.), VIII. X.

• Practice the chords horizontally, beginning with the C chord in each of the given positions; these are their chord tones:
  • III: x1573x. III (no 4th st.): x1x735. VIII: 1x735x. X: xx1573.
• #5ths: CM7#5 / Dm7 / E7 / FM7 / G#dim / AmM7 / Bm7b5
• b3rds: CmM7 / Dm7 / EbM7#5 / F7 / G7 / Am7b5 / Bm7b5
• b9b7: C7 / DbM7#5 / Edim / FM7 / Gm7b5 / Am7 / BbmM7
• b9b3b7: Cm7 / DbM7#5 / Eb7 / F7 / Gm7b5 / Am7b5 / BbmM7
• b9b3b5b7: Cm7b5 / DbM7#5 / Ebm7 / F7 / GbM7 / Adim / BbmM7
• Play world/altered scales and arpeggios over the chords above.
• Memorize each harmonized scale progression.

(These drills are good for an aging brain, fretboard memorization, and for playing more creatively. Improvise with them on your couch with eyes closed–a relaxing, healthy retreat.)